In order to ensure a safer and more reliable flight of civil aircraft, the automatic flight mode suitable for civil aircraft in China is designed. The working mode of the automatic flight system is analyzed. Based on the Matlab platform, the logical relationship between the man-machine interface and the working mode of the automatic flight system is designed and modeled, and the interaction with the corresponding control law of the working mode is realized. The whole process simulation of typical civil aircraft landing verifies the working mode system, which can provide theoretical reference for the engineering application of civil aircraft automatic flight system.