Preventive maintenance is the main measure to restore and maintain the safety and reliability of the aircraft. Its optimization has always been a common concern of aircraft manufacturers and users. This paper researches the international mainstream preventive maintenance task optimization methods and their applicable objects. Based on the S4000P ISMO process which is suitable for equipment, and combined with the characteristics of military aircraft, the original process is personalized adjusted, and the logic process of preventive maintenance task optimization is constructed, which can be used for the optimization analysis of military aircraft preventive maintenance task.