A continuous sliding mode control algorithm is designed to meet the requirements of high precision and strong robustness for the servo system of air defense gun and the disadvantage of chattering in the traditional sliding mode control. The dynamics of the current loop is ignored in the modeling, and it is regarded as a proportional link. The dynamics and target tracking of the gun servo system are analyzed, and the sliding mode control algorithm and the continuous sliding mode tracking algorithm of the gun servo system are studied. The numerical simulation is used to verify. The results show that the algorithm eliminates the system jitter and makes the system have a smaller error, which proves the effectiveness of the theoretical results.