Abstract: It is thought that the internal friction angle of soil remains unchanged in traditional calculation methods for landslides. In fact, the internal friction angle of soil changes with slope sliding. We analyzed the process of landslides in consideration of the change of the internal friction angle of soil by the material point method. In the material point method, material points with regional information discretizes the slope body. It abandons deformed grids after a computational time step. New grids are employed in the next step. For the example in this paper, since the inertia parameter was small, the results in consideration of the change of the internal friction angle of soil are close to those with a fixed value of lower limit parameter. we further compared the influence of different bounds of friction coefficient on the process of landslides. The shape of the landslide will be flatter with larger sliding distance if the bound of friction coefficient being smaller.