Because of the outstanding anti slide ability of pile group, simple construction and low cost, the use of rail anti slide pile to strengthen the slope of open-pit mine has been favored by many mining enterprises. However, the existing research is mainly based on engineering experience and numerical analysis, and there is still a lack of corresponding research on the design theory and method of strengthening slope with iron anti slide pile. By analyzing the actual characteristics of slope reinforced by rail anti slide pile group, an analysis model is established based on the criteria of geometric equivalence and strength equivalence. The model considers the influence of rail pile and slope soil strain softening, and on this basis, an analysis method is established. The centrifugal model test is used to verify the proposed slope stability analysis method strengthened by rail anti slide pile. The results indicate that the analysis methods can well reflect the instability and failure of the slope for the unreinforced slope and the slope strengthened by rail anti slide pile. Taking the actual project as an example, the design method proposed in this study is adopted to design the slope reinforcement scheme in view of the problem that the slope deformation of the waste dump along the slope increases. The monitoring results show that the slope deformation is well controlled and the reinforcement effect is obvious.