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

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2010-01-31</periodOfReport>

    <issuer>
        <issuerCik>0000102212</issuerCik>
        <issuerName>UNIVEST CORP OF PENNSYLVANIA</issuerName>
        <issuerTradingSymbol>UVSP</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001454969</rptOwnerCik>
            <rptOwnerName>BROBST DUANE J</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>363 HIGH STREET</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SOUDERTON</rptOwnerCity>
            <rptOwnerState>PA</rptOwnerState>
            <rptOwnerZipCode>18964</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Executive VP</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>COMMON</value>
            </securityTitle>
            <transactionDate>
                <value>2010-01-31</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>3939</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>20651.7273</value>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>COMMON</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>20651.7273</value>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">RESTRICTED STOCK AWARD; VESTED IN THREE (3) YEARS.</footnote>
        <footnote id="F2">DOES INCLUDE 1,354.7273 SHARES ACQUIRED ON OR AFTER AUGUST 15, 1996 THROUGH THE DIVIDEND REINVESTMENT PLAN AND EMPLOYEE STOCK PURCHASE PLAN.</footnote>
        <footnote id="F3">DOES INCLUDE 7,175 SHARES OF RESTRICTED STOCK.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Jeffrey M. Schweitzer</signatureName>
        <signatureDate>2010-02-02</signatureDate>
    </ownerSignature>
</ownershipDocument>
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X0303
4
2010-01-31
0000102212
UNIVEST CORP OF PENNSYLVANIA
UVSP
0001454969
BROBST DUANE J
363 HIGH STREET
SOUDERTON
PA
18964
0
1
0
0
Executive VP
COMMON
2010-01-31
4
A
0
3939
0
A
20651.7273
D
COMMON
20651.7273
D
RESTRICTED STOCK AWARD; VESTED IN THREE (3) YEARS.
DOES INCLUDE 1,354.7273 SHARES ACQUIRED ON OR AFTER AUGUST 15, 1996 THROUGH THE DIVIDEND REINVESTMENT PLAN AND EMPLOYEE STOCK PURCHASE PLAN.
DOES INCLUDE 7,175 SHARES OF RESTRICTED STOCK.
Jeffrey M. Schweitzer
2010-02-02