Abstract: The slope stability of open−pit polymetallic mines is the key problem to ensure mine safety and environmental protection. In this paper, orthogonal experimental design, limit equilibrium method and FLAC3D numerical simulation are used to systematically analyze the structural parameters of the end slope of an open−pit mine and verify its stability. Through orthogonal experiment design, slope stability parameters under different slope height, slope Angle and geological conditions were investigated, and the safety factor was calculated by using simplified Bishop method and Morgenstern−Price method. The results showed that under natural conditions, the safety coefficient of each slope was greater than 1.17, which was in line with the standard requirements. In order to further verify the stability of the slope, FLAC3D numerical simulation combined with strength reduction method was used for three−dimensional stability analysis. The simulation results showed that there were some risks in the top and local areas of the slope surface, but the overall safety factor was 1.78, indicating that the slope was in a stable state. This study not only provides theoretical basis and practical guidance for slope design and stability evaluation of open−pit mine, but also provides reference for similar engineering projects, which has important value of improving mining safety and prolonging mine life.