Frictional plate is an important component of vehicle transmission system. The frequent braking or clutching working condition makes the frictional plate suffer a large range of impact load. The damage accumulation method of frictional plate under impact load is necessary to accurately predict the lifetime and avoid abrupt damage. In this paper, a non-linear impact damage accumulation model is proposed to study the impact damage of frictional plate. The threshold value is set according to fatigue test results based on the principles that stress cycles with amplitude less than the threshold value lead little damage to frictional plate and damage accumulation is performed only for stress cycles with amplitude larger than the threshold value. The comparison between theoretical calculation result and experimental result shows that the proposed method can be used for the impact damage calculation and lifetime prediction of frictional plate.