All processes of autonomous control are designed for improving the ability of autonomous flight on the small unmanned air vehicle. The research is based on the certain type small fixed-wing unmanned air vehicle in this paper. Firstly, flight control system and guidance laws are promoted, then the velocity of lateral departure from desired flight path was used in tracking flight path mode, at last the flight scene was designed for flight test. The results show that the system could raise the speed and precision in tracking flight path, and control laws and guidance laws are correct and practical. It not only upgrades the degree of autonomous control, but also be prepared for autonomous formation control and the other concerned technologies.