A　performance　evaluation　model　for　spindle-toolholder　joint　system　is　built　by　applying　the　contact　finite　element　method　(FEM).　Contact　detection　is　implemented　at　the　Gaussian　integration　points　of　the　contact　elements.　Contact　state　is　determined　by　calculating　normal　distance　and　normal　contact　force　between　every　two　points　on　the　contact　surface.　Friction　state　is　determined　by　calculating　tangential　contact　force.　The　determinations　are　introduced　into　the　variable　principle　of　nonlinear　FEM　based　on　pure　penalty　method.　The　updated　FE　equations　are　solved　using　the　full　Newton-Raphson　method.　Deformation　and　contact　stress　distribution　are　studied.　The　stiffness　distribution　is　derived　by　calculating　the　displacement　increments　under　the　different　forces,　based　on　the　stiffness　definition.　The　proposed　model　can　well　illustrate　and　evaluate　the　joint　performance.　©　(2013)　Trans　Tech　Publications,　Switzerland.