PCBN cutting tool’s wear in high speed precision reaches tool wear criterion will cause cutting force and cutting temperature increase clearly, chip color change or melt. Even vibration in cutting will influence dimension accuracy and surface quality of workpiece. It is very useful to establish model by FEM simulation of tool wear predicted. The influence of tool wear in cutting conditions will assurance of machining quality and efficiency, decreasing rate of product cost. PCBN cutting tool’s wear is simulated by FEM software Deform 2D, rake face wear state can be analysed by the influence of tools geometric parameters and cutting parameters tool wear.