The selfdeveloped grinder with fiveaxis computer numerical control (CNC) is able to grind the high hardness and complex tools like ball mills and so on, in addition all precision work could be finished in a single setup. The multibody dynamics model and rigid flexible coupling dynamics model were built by using multibody dynamics theory in part. The built dynamics models were used to analyze the machining tolerance in consideration of different feed acceleration, static and dynamic mass ratio and relative stiffness of different coupling of spindle support member. Three kinds of influencing factors for machining accuracy of the grinder are obtained, which can provide certain reference to the design and structural optimization of the tool grinder.