The types of rock mass collapse and deformation on the bank slope of a hydropower station in southwestern China can be divided into toppled buckling，toppled loosening，toppled relaxation，and toppled creep.The plane and spatial distribution characteristics of toppled and deformed rock mass are summarized. Qualitative analysis of stability of toppled rock mass shows that toppled collapse，toppled relaxation and toppled creep have little influence on bank slope stability，while toppled and loose rock mass has greater influence on engineering.The two-dimensional limit equilibrium analysis shows that the overall stability of the toppled and loose rock mass meets the requirements of the code. Threedimensional discrete element analysis shows that the vertical influence range of toppling loosening is above 1600m of the elevation，and the degree of toppling deformation increases with the elevation.