With the development of engineering technology, FEM can be used to simulate metal machining process and gain better understanding of material flow within dies, so as to optimize tooling to eliminate tears, laps and other forging defects. In this paper, the calculated cutting force increases approximately logarithmically, with the simulation of the end milling operation by finite element method, based on the cutting force theory, the cutting forces and tool deflection can be predicted well from the logarithmic rate dependence