Abstract: Abstract: In open-pit mining, technological and safety requirements often result in relatively shallow slopes at the end walls, leaving substantial coal resourcesburied and unutilized.The partitioned mining with internal dumping, however, shortens the exposure time of the end-wall slopes due to the advancement of the internal dumping field, providing conditions for increasing the slope angle. This study proposes an optimal steep slope mining method for end walls to maximize the slope angle, enhance resource recovery, explore the feasibility of steep slope mining, and optimize platform parameters. Taking the west end wall of a certain open-pit mine as a case study, we analyzed the impact of increasing the end-wall slope angle on stability under different slope configurations, and revealed the dynamic relationship between the development of the internal dumping field and the end-wall slope. For the first time, this study integrated the internal dumping boundary constraints and time-dependent slope theory to derive a stability calculation method for end-wall slopes under the dynamic advancement of the internal dumping field. We probed into the influence of internal dumping boundary constraints on the stability and its variation characteristics A numerical model was developed for the end-wall internal dumping boundary constraints to analyze the evolution of slope stability, displacement, and sliding surface area at different intervals of internal dumping advancement. results indicate that, taking a convex slope as an example, as the internal dumping field gradually advanced, the displacement zone of the end-wall slope became increasingly concentrated, and the peak displacement of the upper slope gradually decreased. Within the limit of internal dumping advancement, the stability improvement rate of the end-wall slope increased with decreasingtracking distance of the internal dumping field. Specifically, for every 100 meters reduction in the tracking distance, the displacement zone area of the end-wall slope decreased by 10.37 %, and the rate of peak displacement reduction in the upper slope increased by 8 %.