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

    <schemaVersion>X0202</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2008-01-02</periodOfReport>

    <noSecuritiesOwned>1</noSecuritiesOwned>

    <issuer>
        <issuerCik>0000778164</issuerCik>
        <issuerName>Pacific Ethanol, Inc.</issuerName>
        <issuerTradingSymbol>PEIX</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001291464</rptOwnerCik>
            <rptOwnerName>Hansen Joseph W</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O PACIFIC ETHANOL, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>400 CAPITOL MALL, SUITE 2060</rptOwnerStreet2>
            <rptOwnerCity>SACRAMENTO</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>95814</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Chief Financial Officer</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <footnotes></footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/Joseph W. Hansen</signatureName>
        <signatureDate>2008-01-08</signatureDate>
    </ownerSignature>
</ownershipDocument>
