A　profilometer　can　be　used　to　monitor　the　tooth　surface　topography　evolution　during　gear　pitting　tests.　Due　to　the　mounting　relationship　variation　between　the　instrument　and　the　gear,　the　tooth　profile＇s　measurement　position　deviation　from　its　theoretical　location　will　introduce　a　measurement　error.　In　this　study,　the　tooth　profile　measurement　error　introduced　by　mounting　using　a　tactile　profilometer　was　theoretically　analysed　and　experimentally　confirmed　as　a　fish　shape.　A　mounting　error　compensation　method　based　on　projection　onto　the　perpendicular　plane　to　the　gear＇s　datum　axis　was　proposed.　The　results　show　that　the　fish-shaped　tooth　profile　measurement　error　can　be　effectively　compensated,　benefitting　the　evaluation　of　the　gear　tooth　surface　wear　during　gear　pitting　tests.