It　is　commonly　understood　that　precast　technology　has　been　rapid　development　and　application　due　to　its　short　construction　period　and　environmental　friendly,　etc.　Among　all　precast　structure,　precast　segment　column　has　been　widely　concerned　in　the　substructure　of　bridges.　The　precast　segment　columns　will　not　only　suffer　from　the　earthquake　loads　but　also　be　subjected　to　the　collision　of　vehicle　and　barges.　The　concrete　segments　of　precast　segment　column　subjected　to　vehicle　collision　are　prone　to　slip　and　even　punching　failure.　In　order　to　enhance　the　shear　resistance　between　concrete　segments,　the　precast　segment　column　with　shear　key　is　designed,　and　the　dynamic　performance　and　shear　mechanism　under　vehicle　collision　are　analysed　in　this　work.　The　results　indicate　that　the　shear　key　improves　the　shear　capacity　between　segments　and　effectively　reduces　the　relative　displacement　between　segments,　and　makes　the　deformation　mode　of　precast　segment　column　change　from　shear　type　to　bending　type　under　vehicle　collision.　The　maximum　impact　force　of　precast　segment　column　with　shear　key　is　larger　than　that　without　shear　key.　Besides,　the　shear　mechanism　of　precast　segment　column　is　revealed,　and　the　calculation　formula　of　local　shear　resistance　is　proposed.