Abstract: The deformation and stability of left bank slope B in Longtan Project is the key to safety of the project.Geologic and stability analyses indicate that overall stability of the left bank slope B depends on stability of the slope foot.Therefore,pressing slope foot is taken to stabilize the slope.Numerical simulation method of 3DEC(3D Discrete Element Code) is used to analyze stability of slope B in this paper.The results show: the pressing foot project can actively control the deformation of slope B.Numerical simulation results also match well with monitored displacement of the slope,which proves effectiveness of the pressing foot project on stabilizing the slope.