In CNC machine tools servo feed system, there are many uncertain parameters, it is difficult to establish accurate mathematical model of the Servo feed system. The parameters of conventional PID controller can’t adjust immediately to the controlled object. Fuzzy PID controller , which has the advantages of conventional PID control and fuzzy control, can solve these problems. We apply it in numerical control machine servo feed system. The simulation in MATLAB shows that the fuzzy auto-tuning PID controller improve the dynamic performance of the servo feed system and has better robustness.