<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.26.1</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>348</ContextCount>
  <ElementCount>554</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>false</FootnotesReported>
  <SegmentCount>110</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>11</UnitCount>
  <MyReports>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>995200090 - Document - Document and Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DocumentDocumentAndEntityInformation</Role>
      <ShortName>Document and Entity Information</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>995200100 - Statement - CONSOLIDATED BALANCE SHEETS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/StatementConsolidatedBalanceSheets</Role>
      <ShortName>CONSOLIDATED BALANCE SHEETS</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>995200105 - Statement - CONSOLIDATED BALANCE SHEETS (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/StatementConsolidatedBalanceSheetsParenthetical</Role>
      <ShortName>CONSOLIDATED BALANCE SHEETS (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>995200200 - Statement - CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE (LOSS) INCOME</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/StatementConsolidatedStatementsOfOperationsAndComprehensiveLossIncome</Role>
      <ShortName>CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE (LOSS) INCOME</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>995200205 - Statement - CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE (LOSS) INCOME (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/StatementConsolidatedStatementsOfOperationsAndComprehensiveLossIncomeParenthetical</Role>
      <ShortName>CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE (LOSS) INCOME (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>995200300 - Statement - CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' (DEFICIT) EQUITY</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/StatementConsolidatedStatementsOfChangesInShareholdersDeficitEquity</Role>
      <ShortName>CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' (DEFICIT) EQUITY</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>995200305 - Statement - CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' (DEFICIT) EQUITY (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/StatementConsolidatedStatementsOfChangesInShareholdersDeficitEquityParenthetical</Role>
      <ShortName>CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' (DEFICIT) EQUITY (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>995200400 - Statement - CONSOLIDATED STATEMENTS OF CASH FLOWS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/StatementConsolidatedStatementsOfCashFlows</Role>
      <ShortName>CONSOLIDATED STATEMENTS OF CASH FLOWS</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>995200405 - Statement - CONSOLIDATED STATEMENTS OF CASH FLOWS (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/StatementConsolidatedStatementsOfCashFlowsParenthetical</Role>
      <ShortName>CONSOLIDATED STATEMENTS OF CASH FLOWS (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>995210101 - Disclosure - ORGANIZATION AND NATURE OF OPERATIONS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureOrganizationAndNatureOfOperations</Role>
      <ShortName>ORGANIZATION AND NATURE OF OPERATIONS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>995210201 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureSummaryOfSignificantAccountingPolicies</Role>
      <ShortName>SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>995210301 - Disclosure - SHORT-TERM INVESTMENTS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureShortTermInvestments</Role>
      <ShortName>SHORT-TERM INVESTMENTS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>995210401 - Disclosure - NOTES RECEIVABLE</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureNotesReceivable</Role>
      <ShortName>NOTES RECEIVABLE</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>995210501 - Disclosure - ACCOUNTS RECEIVABLE, NET</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureAccountsReceivableNet</Role>
      <ShortName>ACCOUNTS RECEIVABLE, NET</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>995210601 - Disclosure - INVENTORIES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureInventories</Role>
      <ShortName>INVENTORIES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>995210701 - Disclosure - PREPAYMENTS AND OTHER CURRENT ASSETS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosurePrepaymentsAndOtherCurrentAssets</Role>
      <ShortName>PREPAYMENTS AND OTHER CURRENT ASSETS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>995210801 - Disclosure - PROPERTY AND EQUIPMENT, NET</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosurePropertyAndEquipmentNet</Role>
      <ShortName>PROPERTY AND EQUIPMENT, NET</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>995210901 - Disclosure - INTANGIBLE ASSETS, NET</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureIntangibleAssetsNet</Role>
      <ShortName>INTANGIBLE ASSETS, NET</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>995211001 - Disclosure - LAND-USE RIGHTS, NET</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureLandUseRightsNet</Role>
      <ShortName>LAND-USE RIGHTS, NET</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>995211101 - Disclosure - LONG-TERM INVESTMENTS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureLongTermInvestments</Role>
      <ShortName>LONG-TERM INVESTMENTS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>995211201 - Disclosure - OTHER NON-CURRENT ASSETS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureOtherNonCurrentAssets</Role>
      <ShortName>OTHER NON-CURRENT ASSETS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>21</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>995211301 - Disclosure - BORROWINGS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureBorrowings</Role>
      <ShortName>BORROWINGS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>22</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>995211401 - Disclosure - NOTES PAYABLE</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureNotesPayable</Role>
      <ShortName>NOTES PAYABLE</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>23</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>995211501 - Disclosure - ACCRUED EXPENSES AND OTHER CURRENT LIABILITIES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureAccruedExpensesAndOtherCurrentLiabilities</Role>
      <ShortName>ACCRUED EXPENSES AND OTHER CURRENT LIABILITIES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>24</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>995211601 - Disclosure - LEASES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureLeases</Role>
      <ShortName>LEASES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>25</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>995211701 - Disclosure - ORDINARY SHARES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureOrdinaryShares</Role>
      <ShortName>ORDINARY SHARES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>26</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>995211801 - Disclosure - NET REVENUES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureNetRevenues</Role>
      <ShortName>NET REVENUES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>27</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>995211901 - Disclosure - OTHER OPERATING INCOME, NET</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureOtherOperatingIncomeNet</Role>
      <ShortName>OTHER OPERATING INCOME, NET</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>28</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>995212001 - Disclosure - INCOME TAXES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureIncomeTaxes</Role>
      <ShortName>INCOME TAXES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>29</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>995212101 - Disclosure - SHARE-BASED COMPENSATION</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureShareBasedCompensation</Role>
      <ShortName>SHARE-BASED COMPENSATION</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>30</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>995212201 - Disclosure - RELATED PARTY TRANSACTIONS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureRelatedPartyTransactions</Role>
      <ShortName>RELATED PARTY TRANSACTIONS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>31</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>995212301 - Disclosure - (LOSS) EARNINGS PER SHARE</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureLossEarningsPerShare</Role>
      <ShortName>(LOSS) EARNINGS PER SHARE</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>32</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>995212401 - Disclosure - EMPLOYEE BENEFIT</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureEmployeeBenefit</Role>
      <ShortName>EMPLOYEE BENEFIT</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>33</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>995212501 - Disclosure - STATUTORY RESERVES AND RESTRICTED NET ASSETS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureStatutoryReservesAndRestrictedNetAssets</Role>
      <ShortName>STATUTORY RESERVES AND RESTRICTED NET ASSETS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>34</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>995212601 - Disclosure - COMMITMENTS AND CONTINGENCIES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureCommitmentsAndContingencies</Role>
      <ShortName>COMMITMENTS AND CONTINGENCIES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>35</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>995212701 - Disclosure - SUBSEQUENT EVENT</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureSubsequentEvent</Role>
      <ShortName>SUBSEQUENT EVENT</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>36</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>995212801 - Disclosure - ADDITIONAL INFORMATION OF THE PARENT COMPANY</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureAdditionalInformationOfParentCompany</Role>
      <ShortName>ADDITIONAL INFORMATION OF THE PARENT COMPANY</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>37</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>995410 - Disclosure - Pay vs Performance Disclosure</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/ecd/role/PvpDisclosure</Role>
      <ShortName>Pay vs Performance Disclosure</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>38</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>995447 - Disclosure - Insider Trading Policies and Procedures</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/ecd/role/InsiderTradingPoliciesProc</Role>
      <ShortName>Insider Trading Policies and Procedures</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>39</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>995550 - Disclosure - Cybersecurity Risk Management and Strategy Disclosure</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/cyd/role/CybersecurityRiskManagementAndStrategyDisclosure</Role>
      <ShortName>Cybersecurity Risk Management and Strategy Disclosure</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>40</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>99920202 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureSummaryOfSignificantAccountingPoliciesPolicies</Role>
      <ShortName>SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)</ShortName>
      <MenuCategory>Policies</MenuCategory>
      <Position>41</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>99930203 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureSummaryOfSignificantAccountingPoliciesTables</Role>
      <ShortName>SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.hesaitech.com/role/DisclosureSummaryOfSignificantAccountingPolicies</ParentRole>
      <Position>42</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>99930303 - Disclosure - SHORT-TERM INVESTMENTS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureShortTermInvestmentsTables</Role>
      <ShortName>SHORT-TERM INVESTMENTS (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.hesaitech.com/role/DisclosureShortTermInvestments</ParentRole>
      <Position>43</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>99930503 - Disclosure - ACCOUNTS RECEIVABLE, NET (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureAccountsReceivableNetTables</Role>
      <ShortName>ACCOUNTS RECEIVABLE, NET (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.hesaitech.com/role/DisclosureAccountsReceivableNet</ParentRole>
      <Position>44</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>99930603 - Disclosure - INVENTORIES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureInventoriesTables</Role>
      <ShortName>INVENTORIES (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.hesaitech.com/role/DisclosureInventories</ParentRole>
      <Position>45</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>99930703 - Disclosure - PREPAYMENTS AND OTHER CURRENT ASSETS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosurePrepaymentsAndOtherCurrentAssetsTables</Role>
      <ShortName>PREPAYMENTS AND OTHER CURRENT ASSETS (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.hesaitech.com/role/DisclosurePrepaymentsAndOtherCurrentAssets</ParentRole>
      <Position>46</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>99930803 - Disclosure - PROPERTY AND EQUIPMENT, NET (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosurePropertyAndEquipmentNetTables</Role>
      <ShortName>PROPERTY AND EQUIPMENT, NET (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.hesaitech.com/role/DisclosurePropertyAndEquipmentNet</ParentRole>
      <Position>47</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>99930903 - Disclosure - INTANGIBLE ASSETS, NET (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureIntangibleAssetsNetTables</Role>
      <ShortName>INTANGIBLE ASSETS, NET (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.hesaitech.com/role/DisclosureIntangibleAssetsNet</ParentRole>
      <Position>48</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>99931103 - Disclosure - LONG-TERM INVESTMENTS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureLongTermInvestmentsTables</Role>
      <ShortName>LONG-TERM INVESTMENTS (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.hesaitech.com/role/DisclosureLongTermInvestments</ParentRole>
      <Position>49</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>99931203 - Disclosure - OTHER NON-CURRENT ASSETS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureOtherNonCurrentAssetsTables</Role>
      <ShortName>OTHER NON-CURRENT ASSETS (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.hesaitech.com/role/DisclosureOtherNonCurrentAssets</ParentRole>
      <Position>50</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>99931303 - Disclosure - BORROWINGS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureBorrowingsTables</Role>
      <ShortName>BORROWINGS (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.hesaitech.com/role/DisclosureBorrowings</ParentRole>
      <Position>51</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>99931503 - Disclosure - ACCRUED EXPENSES AND OTHER CURRENT LIABILITIES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureAccruedExpensesAndOtherCurrentLiabilitiesTables</Role>
      <ShortName>ACCRUED EXPENSES AND OTHER CURRENT LIABILITIES (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.hesaitech.com/role/DisclosureAccruedExpensesAndOtherCurrentLiabilities</ParentRole>
      <Position>52</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>99931603 - Disclosure - LEASES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureLeasesTables</Role>
      <ShortName>LEASES (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.hesaitech.com/role/DisclosureLeases</ParentRole>
      <Position>53</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>99931803 - Disclosure - NET REVENUES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureNetRevenuesTables</Role>
      <ShortName>NET REVENUES (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.hesaitech.com/role/DisclosureNetRevenues</ParentRole>
      <Position>54</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>99931903 - Disclosure - OTHER OPERATING INCOME, NET (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureOtherOperatingIncomeNetTables</Role>
      <ShortName>OTHER OPERATING INCOME, NET (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.hesaitech.com/role/DisclosureOtherOperatingIncomeNet</ParentRole>
      <Position>55</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>99932003 - Disclosure - INCOME TAXES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureIncomeTaxesTables</Role>
      <ShortName>INCOME TAXES (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.hesaitech.com/role/DisclosureIncomeTaxes</ParentRole>
      <Position>56</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>99932103 - Disclosure - SHARE-BASED COMPENSATION (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureShareBasedCompensationTables</Role>
      <ShortName>SHARE-BASED COMPENSATION (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.hesaitech.com/role/DisclosureShareBasedCompensation</ParentRole>
      <Position>57</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>99932203 - Disclosure - RELATED PARTY TRANSACTIONS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureRelatedPartyTransactionsTables</Role>
      <ShortName>RELATED PARTY TRANSACTIONS (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.hesaitech.com/role/DisclosureRelatedPartyTransactions</ParentRole>
      <Position>58</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>99932303 - Disclosure - (LOSS) EARNINGS PER SHARE (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureLossEarningsPerShareTables</Role>
      <ShortName>(LOSS) EARNINGS PER SHARE (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.hesaitech.com/role/DisclosureLossEarningsPerShare</ParentRole>
      <Position>59</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R60.htm</HtmlFileName>
      <LongName>99932603 - Disclosure - COMMITMENTS AND CONTINGENCIES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureCommitmentsAndContingenciesTables</Role>
      <ShortName>COMMITMENTS AND CONTINGENCIES (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.hesaitech.com/role/DisclosureCommitmentsAndContingencies</ParentRole>
      <Position>60</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R61.htm</HtmlFileName>
      <LongName>99940101 - Disclosure - ORGANIZATION AND NATURE OF OPERATIONS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureOrganizationAndNatureOfOperationsDetails</Role>
      <ShortName>ORGANIZATION AND NATURE OF OPERATIONS (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.hesaitech.com/role/DisclosureOrganizationAndNatureOfOperations</ParentRole>
      <Position>61</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R62.htm</HtmlFileName>
      <LongName>99940201 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Fair value measurements - Recurring (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureSummaryOfSignificantAccountingPoliciesFairValueMeasurementsRecurringDetails</Role>
      <ShortName>SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Fair value measurements - Recurring (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>62</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R63.htm</HtmlFileName>
      <LongName>99940202 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Fair value measurements - Non-Recurring (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureSummaryOfSignificantAccountingPoliciesFairValueMeasurementsNonRecurringDetails</Role>
      <ShortName>SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Fair value measurements - Non-Recurring (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>63</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R64.htm</HtmlFileName>
      <LongName>99940203 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Accounts receivable, net (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureSummaryOfSignificantAccountingPoliciesAccountsReceivableNetDetails</Role>
      <ShortName>SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Accounts receivable, net (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>64</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R65.htm</HtmlFileName>
      <LongName>99940204 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Property and equipment, net (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureSummaryOfSignificantAccountingPoliciesPropertyAndEquipmentNetDetails</Role>
      <ShortName>SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Property and equipment, net (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>65</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R66.htm</HtmlFileName>
      <LongName>99940205 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Intangible assets (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureSummaryOfSignificantAccountingPoliciesIntangibleAssetsDetails</Role>
      <ShortName>SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Intangible assets (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>66</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R67.htm</HtmlFileName>
      <LongName>99940206 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Revenue recognition (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureSummaryOfSignificantAccountingPoliciesRevenueRecognitionDetails</Role>
      <ShortName>SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Revenue recognition (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>67</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R68.htm</HtmlFileName>
      <LongName>99940207 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Additional information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureSummaryOfSignificantAccountingPoliciesAdditionalInformationDetails</Role>
      <ShortName>SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Additional information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>68</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R69.htm</HtmlFileName>
      <LongName>99940208 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Segment (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureSummaryOfSignificantAccountingPoliciesSegmentDetails</Role>
      <ShortName>SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Segment (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.hesaitech.com/role/DisclosureSummaryOfSignificantAccountingPoliciesTables</ParentRole>
      <Position>69</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R70.htm</HtmlFileName>
      <LongName>99940209 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Foreign currency risk (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureSummaryOfSignificantAccountingPoliciesForeignCurrencyRiskDetails</Role>
      <ShortName>SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Foreign currency risk (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>70</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R71.htm</HtmlFileName>
      <LongName>99940301 - Disclosure - SHORT-TERM INVESTMENTS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureShortTermInvestmentsDetails</Role>
      <ShortName>SHORT-TERM INVESTMENTS (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.hesaitech.com/role/DisclosureShortTermInvestmentsTables</ParentRole>
      <Position>71</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R72.htm</HtmlFileName>
      <LongName>99940401 - Disclosure - NOTES RECEIVABLE (Details)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureNotesReceivableDetails</Role>
      <ShortName>NOTES RECEIVABLE (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.hesaitech.com/role/DisclosureNotesReceivable</ParentRole>
      <Position>72</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R73.htm</HtmlFileName>
      <LongName>99940501 - Disclosure - ACCOUNTS RECEIVABLE, NET (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureAccountsReceivableNetDetails</Role>
      <ShortName>ACCOUNTS RECEIVABLE, NET (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.hesaitech.com/role/DisclosureAccountsReceivableNetTables</ParentRole>
      <Position>73</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R74.htm</HtmlFileName>
      <LongName>99940502 - Disclosure - ACCOUNTS RECEIVABLE, NET - Allowance for credit losses (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureAccountsReceivableNetAllowanceForCreditLossesDetails</Role>
      <ShortName>ACCOUNTS RECEIVABLE, NET - Allowance for credit losses (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>74</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R75.htm</HtmlFileName>
      <LongName>99940601 - Disclosure - INVENTORIES (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureInventoriesDetails</Role>
      <ShortName>INVENTORIES (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.hesaitech.com/role/DisclosureInventoriesTables</ParentRole>
      <Position>75</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R76.htm</HtmlFileName>
      <LongName>99940701 - Disclosure - PREPAYMENTS AND OTHER CURRENT ASSETS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosurePrepaymentsAndOtherCurrentAssetsDetails</Role>
      <ShortName>PREPAYMENTS AND OTHER CURRENT ASSETS (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.hesaitech.com/role/DisclosurePrepaymentsAndOtherCurrentAssetsTables</ParentRole>
      <Position>76</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R77.htm</HtmlFileName>
      <LongName>99940801 - Disclosure - PROPERTY AND EQUIPMENT, NET (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosurePropertyAndEquipmentNetDetails</Role>
      <ShortName>PROPERTY AND EQUIPMENT, NET (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.hesaitech.com/role/DisclosurePropertyAndEquipmentNetTables</ParentRole>
      <Position>77</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R78.htm</HtmlFileName>
      <LongName>99940901 - Disclosure - INTANGIBLE ASSETS, NET (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureIntangibleAssetsNetDetails</Role>
      <ShortName>INTANGIBLE ASSETS, NET (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.hesaitech.com/role/DisclosureIntangibleAssetsNetTables</ParentRole>
      <Position>78</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R79.htm</HtmlFileName>
      <LongName>99940902 - Disclosure - INTANGIBLE ASSETS, NET - Expected amortization expenses (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureIntangibleAssetsNetExpectedAmortizationExpensesDetails</Role>
      <ShortName>INTANGIBLE ASSETS, NET - Expected amortization expenses (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>79</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R80.htm</HtmlFileName>
      <LongName>99941001 - Disclosure - LAND-USE RIGHTS, NET (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureLandUseRightsNetDetails</Role>
      <ShortName>LAND-USE RIGHTS, NET (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.hesaitech.com/role/DisclosureLandUseRightsNet</ParentRole>
      <Position>80</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R81.htm</HtmlFileName>
      <LongName>99941101 - Disclosure - LONG-TERM INVESTMENTS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureLongTermInvestmentsDetails</Role>
      <ShortName>LONG-TERM INVESTMENTS (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.hesaitech.com/role/DisclosureLongTermInvestmentsTables</ParentRole>
      <Position>81</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R82.htm</HtmlFileName>
      <LongName>99941201 - Disclosure - OTHER NON-CURRENT ASSETS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureOtherNonCurrentAssetsDetails</Role>
      <ShortName>OTHER NON-CURRENT ASSETS (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.hesaitech.com/role/DisclosureOtherNonCurrentAssetsTables</ParentRole>
      <Position>82</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R83.htm</HtmlFileName>
      <LongName>99941301 - Disclosure - BORROWINGS - Short-term and long-term borrowings (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureBorrowingsShortTermAndLongTermBorrowingsDetails</Role>
      <ShortName>BORROWINGS - Short-term and long-term borrowings (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>83</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R84.htm</HtmlFileName>
      <LongName>99941302 - Disclosure - BORROWINGS - Principal maturities of the long-term borrowings (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureBorrowingsPrincipalMaturitiesOfLongTermBorrowingsDetails</Role>
      <ShortName>BORROWINGS - Principal maturities of the long-term borrowings (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>84</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R85.htm</HtmlFileName>
      <LongName>99941303 - Disclosure - BORROWINGS - Short-term bank borrowings (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureBorrowingsShortTermBankBorrowingsDetails</Role>
      <ShortName>BORROWINGS - Short-term bank borrowings (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>85</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R86.htm</HtmlFileName>
      <LongName>99941304 - Disclosure - BORROWINGS - Secured bank borrowings related to discounted notes receivable (Details)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureBorrowingsSecuredBankBorrowingsRelatedToDiscountedNotesReceivableDetails</Role>
      <ShortName>BORROWINGS - Secured bank borrowings related to discounted notes receivable (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>86</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R87.htm</HtmlFileName>
      <LongName>99941305 - Disclosure - BORROWINGS - Long-term bank borrowings (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureBorrowingsLongTermBankBorrowingsDetails</Role>
      <ShortName>BORROWINGS - Long-term bank borrowings (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>87</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R88.htm</HtmlFileName>
      <LongName>99941401 - Disclosure - NOTES PAYABLE (Details)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureNotesPayableDetails</Role>
      <ShortName>NOTES PAYABLE (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.hesaitech.com/role/DisclosureNotesPayable</ParentRole>
      <Position>88</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R89.htm</HtmlFileName>
      <LongName>99941501 - Disclosure - ACCRUED EXPENSES AND OTHER CURRENT LIABILITIES (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureAccruedExpensesAndOtherCurrentLiabilitiesDetails</Role>
      <ShortName>ACCRUED EXPENSES AND OTHER CURRENT LIABILITIES (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.hesaitech.com/role/DisclosureAccruedExpensesAndOtherCurrentLiabilitiesTables</ParentRole>
      <Position>89</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R90.htm</HtmlFileName>
      <LongName>99941601 - Disclosure - LEASES - Lease Liabilities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureLeasesLeaseLiabilitiesDetails</Role>
      <ShortName>LEASES - Lease Liabilities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>90</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R91.htm</HtmlFileName>
      <LongName>99941602 - Disclosure - LEASES - Maturities Of Lease Liabilities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureLeasesMaturitiesOfLeaseLiabilitiesDetails</Role>
      <ShortName>LEASES - Maturities Of Lease Liabilities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>91</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R92.htm</HtmlFileName>
      <LongName>99941701 - Disclosure - ORDINARY SHARES (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureOrdinarySharesDetails</Role>
      <ShortName>ORDINARY SHARES (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.hesaitech.com/role/DisclosureOrdinaryShares</ParentRole>
      <Position>92</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R93.htm</HtmlFileName>
      <LongName>99941801 - Disclosure - NET REVENUES (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureNetRevenuesDetails</Role>
      <ShortName>NET REVENUES (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.hesaitech.com/role/DisclosureNetRevenuesTables</ParentRole>
      <Position>93</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R94.htm</HtmlFileName>
      <LongName>99941802 - Disclosure - NET REVENUES - Revenues disaggregated by geographic location (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureNetRevenuesRevenuesDisaggregatedByGeographicLocationDetails</Role>
      <ShortName>NET REVENUES - Revenues disaggregated by geographic location (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>94</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R95.htm</HtmlFileName>
      <LongName>99941803 - Disclosure - NET REVENUES - Accounts receivable and contract balances (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureNetRevenuesAccountsReceivableAndContractBalancesDetails</Role>
      <ShortName>NET REVENUES - Accounts receivable and contract balances (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>95</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R96.htm</HtmlFileName>
      <LongName>99941901 - Disclosure - OTHER OPERATING INCOME, NET (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureOtherOperatingIncomeNetDetails</Role>
      <ShortName>OTHER OPERATING INCOME, NET (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.hesaitech.com/role/DisclosureOtherOperatingIncomeNetTables</ParentRole>
      <Position>96</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R97.htm</HtmlFileName>
      <LongName>99942001 - Disclosure - INCOME TAXES (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureIncomeTaxesDetails</Role>
      <ShortName>INCOME TAXES (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.hesaitech.com/role/DisclosureIncomeTaxesTables</ParentRole>
      <Position>97</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R98.htm</HtmlFileName>
      <LongName>99942002 - Disclosure - INCOME TAXES - Current and deferred portion (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureIncomeTaxesCurrentAndDeferredPortionDetails</Role>
      <ShortName>INCOME TAXES - Current and deferred portion (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>98</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R99.htm</HtmlFileName>
      <LongName>99942003 - Disclosure - INCOME TAXES - Net (loss) income before income tax (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureIncomeTaxesNetLossIncomeBeforeIncomeTaxDetails</Role>
      <ShortName>INCOME TAXES - Net (loss) income before income tax (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>99</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R100.htm</HtmlFileName>
      <LongName>99942004 - Disclosure - INCOME TAXES - Reconciliation between the Effective and Statutory Income Tax Rate (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureIncomeTaxesReconciliationBetweenEffectiveAndStatutoryIncomeTaxRateDetails</Role>
      <ShortName>INCOME TAXES - Reconciliation between the Effective and Statutory Income Tax Rate (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>100</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R101.htm</HtmlFileName>
      <LongName>99942005 - Disclosure - INCOME TAXES - Deferred tax assets and deferred tax liabilities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureIncomeTaxesDeferredTaxAssetsAndDeferredTaxLiabilitiesDetails</Role>
      <ShortName>INCOME TAXES - Deferred tax assets and deferred tax liabilities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>101</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R102.htm</HtmlFileName>
      <LongName>99942006 - Disclosure - INCOME TAXES - Movement of valuation allowance (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureIncomeTaxesMovementOfValuationAllowanceDetails</Role>
      <ShortName>INCOME TAXES - Movement of valuation allowance (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>102</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R103.htm</HtmlFileName>
      <LongName>99942101 - Disclosure - SHARE-BASED COMPENSATION - 2021 Plan (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureShareBasedCompensation2021PlanDetails</Role>
      <ShortName>SHARE-BASED COMPENSATION - 2021 Plan (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>103</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R104.htm</HtmlFileName>
      <LongName>99942102 - Disclosure - SHARE-BASED COMPENSATION - Option awards to new incentive recipients (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureShareBasedCompensationOptionAwardsToNewIncentiveRecipientsDetails</Role>
      <ShortName>SHARE-BASED COMPENSATION - Option awards to new incentive recipients (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>104</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R105.htm</HtmlFileName>
      <LongName>99942103 - Disclosure - SHARE-BASED COMPENSATION - Assumptions used to estimate the fair values of the share options granted (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureShareBasedCompensationAssumptionsUsedToEstimateFairValuesOfShareOptionsGrantedDetails</Role>
      <ShortName>SHARE-BASED COMPENSATION - Assumptions used to estimate the fair values of the share options granted (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>105</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R106.htm</HtmlFileName>
      <LongName>99942104 - Disclosure - SHARE-BASED COMPENSATION - Option activity (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureShareBasedCompensationOptionActivityDetails</Role>
      <ShortName>SHARE-BASED COMPENSATION - Option activity (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>106</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R107.htm</HtmlFileName>
      <LongName>99942105 - Disclosure - SHARE-BASED COMPENSATION - Restricted share units ("RSUs") (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureShareBasedCompensationRestrictedShareUnitsrsusDetails</Role>
      <ShortName>SHARE-BASED COMPENSATION - Restricted share units ("RSUs") (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>107</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R108.htm</HtmlFileName>
      <LongName>99942106 - Disclosure - SHARE-BASED COMPENSATION - Tandem award (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureShareBasedCompensationTandemAwardDetails</Role>
      <ShortName>SHARE-BASED COMPENSATION - Tandem award (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>108</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R109.htm</HtmlFileName>
      <LongName>99942107 - Disclosure - SHARE-BASED COMPENSATION - Share-based compensation (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureShareBasedCompensationShareBasedCompensationDetails</Role>
      <ShortName>SHARE-BASED COMPENSATION - Share-based compensation (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>109</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R110.htm</HtmlFileName>
      <LongName>99942201 - Disclosure - RELATED PARTY TRANSACTIONS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureRelatedPartyTransactionsDetails</Role>
      <ShortName>RELATED PARTY TRANSACTIONS (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.hesaitech.com/role/DisclosureRelatedPartyTransactionsTables</ParentRole>
      <Position>110</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R111.htm</HtmlFileName>
      <LongName>99942301 - Disclosure - (LOSS) EARNINGS PER SHARE (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureLossEarningsPerShareDetails</Role>
      <ShortName>(LOSS) EARNINGS PER SHARE (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.hesaitech.com/role/DisclosureLossEarningsPerShareTables</ParentRole>
      <Position>111</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R112.htm</HtmlFileName>
      <LongName>99942302 - Disclosure - (LOSS) EARNINGS PER SHARE - Anti-dilutive securities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureLossEarningsPerShareAntiDilutiveSecuritiesDetails</Role>
      <ShortName>(LOSS) EARNINGS PER SHARE - Anti-dilutive securities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>112</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R113.htm</HtmlFileName>
      <LongName>99942401 - Disclosure - EMPLOYEE BENEFIT (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureEmployeeBenefitDetails</Role>
      <ShortName>EMPLOYEE BENEFIT (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.hesaitech.com/role/DisclosureEmployeeBenefit</ParentRole>
      <Position>113</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R114.htm</HtmlFileName>
      <LongName>99942501 - Disclosure - STATUTORY RESERVES AND RESTRICTED NET ASSETS - (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureStatutoryReservesAndRestrictedNetAssetsDetails</Role>
      <ShortName>STATUTORY RESERVES AND RESTRICTED NET ASSETS - (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.hesaitech.com/role/DisclosureStatutoryReservesAndRestrictedNetAssets</ParentRole>
      <Position>114</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R115.htm</HtmlFileName>
      <LongName>99942601 - Disclosure - COMMITMENTS AND CONTINGENCIES - Capital expenditure commitments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureCommitmentsAndContingenciesCapitalExpenditureCommitmentsDetails</Role>
      <ShortName>COMMITMENTS AND CONTINGENCIES - Capital expenditure commitments (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>115</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R116.htm</HtmlFileName>
      <LongName>99942602 - Disclosure - COMMITMENTS AND CONTINGENCIES - Royalty commitments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureCommitmentsAndContingenciesRoyaltyCommitmentsDetails</Role>
      <ShortName>COMMITMENTS AND CONTINGENCIES - Royalty commitments (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>116</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R117.htm</HtmlFileName>
      <LongName>99942701 - Disclosure - SUBSEQUENT EVENT (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureSubsequentEventDetails</Role>
      <ShortName>SUBSEQUENT EVENT (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.hesaitech.com/role/DisclosureSubsequentEvent</ParentRole>
      <Position>117</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R118.htm</HtmlFileName>
      <LongName>99942801 - Disclosure - ADDITIONAL INFORMATION OF THE PARENT COMPANY - CONDENSED BALANCE SHEETS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureAdditionalInformationOfParentCompanyCondensedBalanceSheetsDetails</Role>
      <ShortName>ADDITIONAL INFORMATION OF THE PARENT COMPANY - CONDENSED BALANCE SHEETS (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>118</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R119.htm</HtmlFileName>
      <LongName>99942802 - Disclosure - ADDITIONAL INFORMATION OF THE PARENT COMPANY - CONDENSED BALANCE SHEETS - Additional (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureAdditionalInformationOfParentCompanyCondensedBalanceSheetsAdditionalDetails</Role>
      <ShortName>ADDITIONAL INFORMATION OF THE PARENT COMPANY - CONDENSED BALANCE SHEETS - Additional (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>119</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R120.htm</HtmlFileName>
      <LongName>99942803 - Disclosure - ADDITIONAL INFORMATION OF THE PARENT COMPANY - CONDENSED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (INCOME) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureAdditionalInformationOfParentCompanyCondensedStatementsOfOperationsAndComprehensiveLossIncomeDetails</Role>
      <ShortName>ADDITIONAL INFORMATION OF THE PARENT COMPANY - CONDENSED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (INCOME) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>120</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R121.htm</HtmlFileName>
      <LongName>99942804 - Disclosure - ADDITIONAL INFORMATION OF THE PARENT COMPANY - CONDENSED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (INCOME) - Additional (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureAdditionalInformationOfParentCompanyCondensedStatementsOfOperationsAndComprehensiveLossIncomeAdditionalDetails</Role>
      <ShortName>ADDITIONAL INFORMATION OF THE PARENT COMPANY - CONDENSED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (INCOME) - Additional (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>121</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R122.htm</HtmlFileName>
      <LongName>99942805 - Disclosure - ADDITIONAL INFORMATION OF THE PARENT COMPANY - CONDENSED STATEMENTS OF CASH FLOWS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureAdditionalInformationOfParentCompanyCondensedStatementsOfCashFlowsDetails</Role>
      <ShortName>ADDITIONAL INFORMATION OF THE PARENT COMPANY - CONDENSED STATEMENTS OF CASH FLOWS (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>122</Position>
    </Report>
    <Report instance="hsai-20251231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R123.htm</HtmlFileName>
      <LongName>99942806 - Disclosure - ADDITIONAL INFORMATION OF THE PARENT COMPANY - Notes to Schedule I (Details)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.hesaitech.com/role/DisclosureAdditionalInformationOfParentCompanyNotesToScheduleIDetails</Role>
      <ShortName>ADDITIONAL INFORMATION OF THE PARENT COMPANY - Notes to Schedule I (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>123</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <InputFiles>
    <File>hsai-20251231.xsd</File>
    <File>hsai-20251231_cal.xml</File>
    <File>hsai-20251231_def.xml</File>
    <File>hsai-20251231_lab.xml</File>
    <File>hsai-20251231_pre.xml</File>
    <File doctype="20-F" isDefinitelyFs="true" isUsgaap="true" original="hsai-20251231x20f.htm">hsai-20251231x20f.htm</File>
  </InputFiles>
  <SupplementalFiles>
    <File>hsai-20251231x20f003.jpg</File>
    <File>hsai-20251231x20f004.jpg</File>
    <File>hsai-20251231x20f005.jpg</File>
    <File>hsai-20251231x20f006.jpg</File>
    <File>hsai-20251231x20f007.jpg</File>
    <File>hsai-20251231x20f008.jpg</File>
    <File>hsai-20251231x20f009.jpg</File>
    <File>hsai-20251231x20f010.jpg</File>
    <File>hsai-20251231x20f012.jpg</File>
  </SupplementalFiles>
  <BaseTaxonomies>
    <BaseTaxonomy items="1">http://fasb.org/srt/2025</BaseTaxonomy>
    <BaseTaxonomy items="1520">http://fasb.org/us-gaap/2025</BaseTaxonomy>
    <BaseTaxonomy items="14">http://xbrl.sec.gov/cyd/2025</BaseTaxonomy>
    <BaseTaxonomy items="51">http://xbrl.sec.gov/dei/2025</BaseTaxonomy>
    <BaseTaxonomy items="1">http://xbrl.sec.gov/ecd/2025</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>