Abstract: To reveal the mechanism of the influence of external loading on the stability of open-pit mine slopes，and to quantitatively analyze the regulatory effect of different thicknesses of safety pillars on the stability of the mine slopes，this study provides a theoretical basis for selecting safe，efficient，and eco⁃ nomically reasonable schemes for mines. Taking a certain solid waste landfill and the proposed newly-built open-pit mine slope as the research objects，based on thorough investigation of the engineering and hydro⁃ geological conditions of the mine and the solid waste landfill，the Morgenstern-Price method and the sim⁃ plified Bishop method in the limit equilibrium method were used to calculate the stability of the open-pit mine slope under the condition of a 10~40 m thick safety pillar. The results show that the existence of the solid waste landfill has changed the external topography and geomorphology of the mine slope. The infiltra⁃ tion of rainfall and the strong water absorption of titanium gypsum sludge have led to the southern slope of the mining area being affected by groundwater. As the thickness of the safety pillar increases，the influence of the groundwater of the solid waste landfill on the mine slope becomes smaller and smaller. The adoption of the safety pillar method can effectively increase the stability of the mine slope. With the continuous in⁃crease in the thickness of the safety pillar，the rate of change of the safety factor of the mine slope shows a trend of being faster at the beginning and then slower. From the perspectives of safety and economy，setting a 30 m thick safety pillar between the newly-built mine and the solid waste landfill is the optimal choice. It not only meets the requirements of slope stability norms，ensures the safety of the mine production，but al⁃ so takes into account economy and avoids resource waste caused by setting an overly thick safety pillar.

Key words: solid waste landfill, slope stability, safety pillar, limit equilibrium method