The paper take the landslide in the left bank of a hydropower station in Southwest of China as the research object. A 3D numerical simulation model is developed to analyze the deformation features and stability of the accumulation body on the theory of The strength reduction method by FLAC3D. The research results show that the accumulation body is stable under natural conditions. The results are also consistent with the spot geological surveys which prove the appropriateness of parameters choosing and the reliability of 3D calculation model.