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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2016-02-04</periodOfReport>

    <notSubjectToSection16>1</notSubjectToSection16>

    <issuer>
        <issuerCik>0000924719</issuerCik>
        <issuerName>SMITH MIDLAND CORP</issuerName>
        <issuerTradingSymbol>SMID</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001504393</rptOwnerCik>
            <rptOwnerName>Tall Cotton Partners, LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O VIRGINIA CAPITAL PARTNERS</rptOwnerStreet1>
            <rptOwnerStreet2>1801 LIBBIE AVENUE, SUITE 201</rptOwnerStreet2>
            <rptOwnerCity>RICHMOND</rptOwnerCity>
            <rptOwnerState>VA</rptOwnerState>
            <rptOwnerZipCode>23226</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001534451</rptOwnerCik>
            <rptOwnerName>Russell Frederick L. Jr.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O VIRGINIA CAPITAL PARTNERS</rptOwnerStreet1>
            <rptOwnerStreet2>1801 LIBBIE AVENUE, SUITE 201</rptOwnerStreet2>
            <rptOwnerCity>RICHMOND</rptOwnerCity>
            <rptOwnerState>VA</rptOwnerState>
            <rptOwnerZipCode>23226</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001534371</rptOwnerCik>
            <rptOwnerName>Virginia Capital II, LP</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O VIRGINIA CAPITAL PARTNERS</rptOwnerStreet1>
            <rptOwnerStreet2>1801 LIBBIE AVENUE, SUITE 201</rptOwnerStreet2>
            <rptOwnerCity>RICHMOND</rptOwnerCity>
            <rptOwnerState>VA</rptOwnerState>
            <rptOwnerZipCode>23226</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001534372</rptOwnerCik>
            <rptOwnerName>Virginia Capital Partners II, LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O VIRGINIA CAPITAL PARTNERS</rptOwnerStreet1>
            <rptOwnerStreet2>1801 LIBBIE AVENUE, SUITE 201</rptOwnerStreet2>
            <rptOwnerCity>RICHMOND</rptOwnerCity>
            <rptOwnerState>VA</rptOwnerState>
            <rptOwnerZipCode>23226</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001534373</rptOwnerCik>
            <rptOwnerName>Virginia Capital Partners, LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O VIRGINIA CAPITAL PARTNERS</rptOwnerStreet1>
            <rptOwnerStreet2>1801 LIBBIE AVENUE, SUITE 201</rptOwnerStreet2>
            <rptOwnerCity>RICHMOND</rptOwnerCity>
            <rptOwnerState>VA</rptOwnerState>
            <rptOwnerZipCode>23226</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2016-02-04</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>180166</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>2.19</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>387197</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes></footnotes>

    <remarks>Shares are owned directly by Tall Cotton Partners, LLC (&quot;TCP&quot;).  Virginia Capital II, LP (&quot;VCP II, LP&quot;) owns a majority of the voting interests in TCP, and Virginia Capital Partners II, LLC (&quot;VCP II&quot;) is the sole manager of TCP.  VCP II is the general partner of VCP II LP. Virginia Capital Partners, LLC (&quot;VCP&quot;) is the sole owner of VCP II.  Frederick L. Russell, Jr. controls VCP.  None of BCP II LP, VCP II, BCP or Mr. Russell holds any shares of the issuer directly but may be deemed to indirectly beneficially own the shares of the issuer held by TCP.  Each of the reporting persons disclaims beneficial ownership of the reported securities except to the extent of his or its pecuniary interest therein.</remarks>

    <ownerSignature>
        <signatureName>/s/ Frederick L. Russell, Jr., President of Virginia Capital Partners II, LLC, Manager of Tall Cotton Partners, LLC</signatureName>
        <signatureDate>2016-02-08</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Frederick L. Russell, Jr.</signatureName>
        <signatureDate>2016-02-08</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Frederick L. Russell, Jr., Manager of Virginia Capital Partners II, LLC, General Partner of Virginia Capital  II, LP</signatureName>
        <signatureDate>2016-02-08</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Frederick L. Russell, Jr., Manager</signatureName>
        <signatureDate>2016-02-08</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Frederick L. Russell, Jr., Manager</signatureName>
        <signatureDate>2016-02-08</signatureDate>
    </ownerSignature>
</ownershipDocument>
