Based on the process of orifice chamfer machining with inner R forming milling cutter, orthogonal milling experiments on TB6 were carried out to analyze the influence of maximum cutting speed vc, feed per tooth fz and cutting depth ap on the fatigue life of test specimens. The results show that the effect of feed per tooth on fatigue life is more pronounced than the effects of cutting depth and cutting speed. Meanwhile, under the milling conditions of experiments, the milling parameters are developed as vc=20m/min, fz=0.04–0.08mm/z, ap=0.1mm, which can make the fatigue life longest.