Abstract: The material point method, employing updated Lagrangian formulation, can be used to simulate the failure process of slopes. The strength reduction material point method is proposed to analyze slope stability, based on the generalized interpolation material point method and the elastoplastic constitutive model. The detailed procedure is as follows. Firstly, the grid is divided and all the material points are identified. Then, an incremental gravitation model is employed to eliminate the stress oscillation and to determine the initial stress field of slope. Finally, the parameters of the soil strength are reduced, and the safety factor is determined according to the distribution of the plastic zone as well as the deformation of the soil. The illustration shows the results of the strength reduction material point method are almost identical with those of strength reduction finite element method. Meanwhile, the slope failure criterion of the strength reduction material point method may use the fact whether a sudden displacement change occurs along the vertical direction of the slope crest. Also, using strength reduction material point method, it is discovered that even the plastic zone breaks through under a certain reduction coefficient, the slope still remains stable, and no sudden displacement change will occur immediately. The proposed method offers a new idea for the analysis of slope stability.