Abstract:The quality of flight control system was affected by the self-oscillation of the backlash nonlinearity of rudder system. The problem was analyzed from the aspect of flight control system. A mathematical model of rolling channel based on description function method was established, which was contrasted and analyzed from three aspects of rapidity, damping characteristic and inherent damping of the vehicle. The results showed that the increa-sing of inherent damping can effectively reduce or even eliminate the phenomenon of self-oscillation caused by the backlash nonlinearity of the rudder system.