It introduces the trailing-edge flap of High Lift System architecture and failure type of some civil airplanes, describe the failure type of the asymmetry fault and the skew fault of the trailing-edge flap. As for how to monitor and protect the asymmetry fault and the skew fault question, it research and analysis the monitor and protection method as well as working logic of the both type faults, during making sure the threshold parameter of the working logic roundly considering the process to check and ensure the fault, and the brake process of Flap Power Drive Unit as well as the system mechanical error, and so on. Lastly it builds the Simulink model of the fault protection work logic, and simulinks several different failure conditions, the result indicates the fault protection method can monitor system and prevent fault spreading. using for reference to design of civil airplane High Lift system.