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

    <schemaVersion>X0206</schemaVersion>

    <documentType>3/A</documentType>

    <periodOfReport>2019-06-05</periodOfReport>

    <dateOfOriginalSubmission>2019-06-05</dateOfOriginalSubmission>

    <noSecuritiesOwned>1</noSecuritiesOwned>

    <issuer>
        <issuerCik>0001770141</issuerCik>
        <issuerName>GigCapital2, Inc.</issuerName>
        <issuerTradingSymbol>GIX.U</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001745039</rptOwnerCik>
            <rptOwnerName>McDonough Tara M</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O GIGCAPITAL2, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>2479 E. BAYSHORE RD., SUITE 200</rptOwnerStreet2>
            <rptOwnerCity>PALO ALTO</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94303</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Chief Financial Officer &amp; VP</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <footnotes></footnotes>

    <remarks>This amendment is being filed to report that as of the effectiveness of the Registration Statement zero (0) shares of Common Stock were held by Ms. McDonough.</remarks>

    <ownerSignature>
        <signatureName>/s/ Tara McDonough</signatureName>
        <signatureDate>2019-06-07</signatureDate>
    </ownerSignature>
</ownershipDocument>
