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

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2004-11-11</periodOfReport>

    <issuer>
        <issuerCik>0000028367</issuerCik>
        <issuerName>Comtech Group Inc</issuerName>
        <issuerTradingSymbol>COGO,OB</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001297604</rptOwnerCik>
            <rptOwnerName>Kang Jingwei</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O COMTECH GROUP, ROOM 1001, TOWER C,</rptOwnerStreet1>
            <rptOwnerStreet2>SKYWORTH BLDG, HIGH TECH INDUSTRIAL PK.</rptOwnerStreet2>
            <rptOwnerCity>NANSHAN, SHENZHEN</rptOwnerCity>
            <rptOwnerState></rptOwnerState>
            <rptOwnerZipCode>5180 PRC</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>CEO and President</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock, $0.01 par value</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>37261978</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See Note</value>
                    <footnoteId id="F1"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Options to purchase Common Stock</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>1.87</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2004-11-11</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>1000000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2007-11-11</value>
            </exerciseDate>
            <expirationDate>
                <value>2014-11-11</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock, $0.01 par value</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>1000000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1000000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Includes (i) 26,326,398 shares beneficially owned by Comtech Global Investment Ltd., over which Mr. Kang and his wife, Ms. Nan Ji, share voting and investment power, and (ii) 10,935,580 shares beneficially owned by Ren Investment International Ltd., over which Mr. Kang, as sole director, has sole voting and investment power.  Mr. Kang does not own any shares of Ren Investment International.</footnote>
        <footnote id="F2">Not applicable.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Jeffrey Kang</signatureName>
        <signatureDate>2004-12-21</signatureDate>
    </ownerSignature>
</ownershipDocument>

