Abstract: The Wenchuan 8.0 earthquake triggered a huge number of rockfall hazards. The hazards most happened in cataclastic rock mass. The respective stability of the back wall and the front accumulation of the slope and the influence of the back wall upon the stability of accumulation are problems that are faced by people after the earthquake. This paper takes the Ganhekou rockfalling accumulation as a example. It is based on analysis of the structure feature and genetic mechanism of the slope. It uses the 2D Discrete Element MethodUDEC to simulate the stability status and possible failure process of the slope under nature or earthquake condition.It uses the limit equilibrium theory based models and analyse the stability of accumulation before or after loaded by new substance generated by new rockfall. The results show that the genetic process of rockfalling accumulation can divided to stress redistribution, the formation of potential rockfall mass and rockfall induced by earthquake three phases. Before loading function, the accumulation is relatively stable both under nature or earthquake condition. But after considering the function of loading, it may fail under earthquake. The combined use of discrete element method and limit equilibrium method are practicable way for solving similar problem of similar slopes.