In order to improve the autonomy, reliability and high accuracy of UAV, the high accuracy of SINS in short time, Doppler velocity measurement and terrain matching position are taken full advantage based on analyzing the characteristic of SINS, Doppler and digital map. The distributed fault tolerance integrated navigation system based on SINS/Doppler/Terrain matching is studied. Simulation experiments show that the navigation system could realize a high accuracy positioning and orientation, have some ability of fault tolerance, and very important for engineering applications.