This study uses the Taguchi method for the optimal processing parameter design of end-milling for high speed the cutting of SKD61 mold steel. Tool life is the major performance index of the cutting process. The cutting processing parameters of end-milling for high speed cutting are spindle speed, feed per tooth, radial depth of cut, axial depth of cut, helix angle, radial rake angle, radial relief angle, axial rake angle and axial relief angle. The optimal processing parameters can be evaluated by the Taguchi method. The results of confirmation experiments show that the Taguchi method can be effectively used to evaluate the optimal processing parameters. Thus, the tool life of high speed cutting tools for SKD61 mold steel can be improved effectively.