The yaw control system is the critical system to ensure the safe-flight of civil aircraft. Its performance not only directly affects the control quality and performance of the aircraft, but also endangers the flight safety of the aircraft in the failure state. As the main control surface of the yaw control, the authority management, redundancy configuration and stability design of the rudder need high reliability and safety. It is necessary to design measures to avoid the bad coupling between the system and the elastic mode of the aircraft.