In order to improve control precision of missile servo system, by combining fuzzy control theory with PID control method, the fuzzy self-tuning control algorithm was proposed for missile servo system. On the basis of explanation of the controller's structure, the idea and formula of the algorithm were described in detail. Then, the software design flow of the algorithm was analyzed. Simulation shows that, compared with current fitting method and conventional PID method, the fuzzy self-tuning method is obviously superior in shortening output response time of missile servo system and improving disturbance stability, and is promising in engineering application.