Abstract：First of all，according to the research on the transverse sections of the stable nature slope in the engineering area，the slope shape data of the sand-slate and marble slopes are gained. Secondly，in combination with data acquired from some slopes of the being built or built hydropower stations and natural slopes，the excavation angle is recommended for the dam abutment slope from perspective of geology. Thirdly，based on the characters research of the deep fracture at the left abutment slope in detail，the failure mode of the abutment slope and boundary condition of the potential failure block after excavation are analysed. During the analyses，3D rigid limit equilibrium method is used to analyze the stability of the potential failure block in abutment slope in the nature and excavated stages individually. What is more，the computation model can be established massively or sectionally according to the assumption of different boundary conditions of the potential failure block. Finally，through comprehensive analysis，the conclusion that the sectional computation model is accordance with the dam abutment slope engineering is drawn. Reinforcement measures are put forward for the high slopes. The results can not only solve the practical engineering problems but also provide some referential experiences for similar projects.
