Abstract: The location of slip surface is featured by the shear strain rate obtained by the shear strength reduction method. The controlling points are set on the slope surface to form the controlling line, then the points with the maximum shear strain rate along the controlling lines are found and connected to form the slip surface. The data of the slip surface is obtained by the FISH program to quantitate the slip surface. The influence of each parameter on the slip surface is analyzed, showing that the locations of slip surface obtained from shear strain rate by the strength reduction method and the limit equilibrium method are basically the same, which validates the correctness of the proposed method. With the increase of cohesion, the type of slip changes from shallow slip to deep one, and the slope of slip surface becomes less steeper and the slip volume becomes larger. With the increase of internal friction angle, the type of slip changes from deep slip to shallow one, then the slip surface becomes steeper and the upper vertex of slip surface comes closer to the top of slope. The tensile strength has little impact on the factor of safety and the slip surface of slope.