<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4/A</documentType>

    <periodOfReport>2010-12-02</periodOfReport>

    <dateOfOriginalSubmission>2010-12-06</dateOfOriginalSubmission>

    <issuer>
        <issuerCik>0000045012</issuerCik>
        <issuerName>HALLIBURTON CO</issuerName>
        <issuerTradingSymbol>HAL</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001423056</rptOwnerCik>
            <rptOwnerName>Lotfy Ahmed H M</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>14TH FLOOR, CITIBANK TOWER</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>DUBAI</rptOwnerCity>
            <rptOwnerState>C0</rptOwnerState>
            <rptOwnerZipCode>000000</rptOwnerZipCode>
            <rptOwnerStateDescription>UNITED ARAB EMIRATES</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>President - Eastern Hemisphere</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2010-12-02</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>D</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>1648</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>40.61</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>119179</value>
                    <footnoteId id="F3"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Shares transferred to Halliburton Company for payment for Federal tax withholding obligations on lapse of restrictions on shares issued under the Stock and Incentive Plan.  Said Plan permits Reporting Person to satisfy withholding tax obligation by transferring unrestricted shares to the Issuer.</footnote>
        <footnote id="F2">Due to a miscalculation in tax withholding obligations, the amount of shares transferred for payment of taxes was misstated in the Form 4 filed on December 6, 2010.  This Amended Form 4 is being filed to report the correct amount of shares withheld for taxes.</footnote>
        <footnote id="F3">Due to the miscalculation in the tax withholding obligations originally reported in the Form 4 filed on December 6, 2010, the amount of securities beneficially owned was misstated.  This Amendment is filed to report the correct amount of securities beneficially owned.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Robert L. Hayter, by Power of Attorney</signatureName>
        <signatureDate>2010-12-23</signatureDate>
    </ownerSignature>
</ownershipDocument>
