The flight envelope of aircraft is wide and complex, it is impossible to obtain an accurate aircraft mathematic mode, and the flight performance is not good by utilizing the conventional control theory. Since the aircraft is very complex, it is necessary that the flight control system possesses a strong robust stability. The sliding mode variable structure control just has the advantage of the strong robust stability, therefore, in this paper, the sliding mode control theory is used in designing the controller for the flight control system. First, the PI type mode is designed in order to reduce the error of stable state. Second, Pole assignment method is used to cope with the mode poles so that the mode has the good response. Third, the simple saturating control is adopted to eliminate the chattering phenomena. Finally, the controller for the flight control system is designed. The simulation results show that the whole control system has good a stability and performance.