To　improve　measurement　precision　in　laser　heterodyne　interferometry,　the　influences　of　polarization　beam　splitter　(PBS)　upon　nonlinearity　must　be　determinated.　Based　on　the　mechanism　of　nonlinearity,　the　model　about　how　the　first-harmonic　and　second-harmonic　nonlinearities　are　affected　by　PBS　is　proposed.　The　simulation　results　show　that　the　PBS　which　is　of　feeble　transmissivity　and　strong　reflectivity　should　be　selected　to　reduce　nonlinearity　error.　When　nonorthogonal　error　of　laser　beams　is　5°,　and　reflectivity　of　PBS　is　ideal,　the　transmissivity　reduces　from　1　to　0.90,　nonlinearity　reduces　from　4.41　nm　to　4.19　nm.　The　first　harmonic　nonlinearity　is　compensated　by　adjusting　rotation　angle　of　PBS.　When　rotation　angle　of　PBS　is　5°,　and　reflectivity　of　PBS　is　ideal,　the　transmissivity　is　reduced　from　1　to　0.90,　nonlinearity　is　reduced　from　4.41　nm　to　2.56　nm.