Abstract: To study the dynamic stability of the end-slope, reduce the mining area and save coal resources in the process of steep end-slope mining, according to the basic principles of geometry, the relationship between the forward distance of the lower step and the angle of the end-slope is analyzed. FLAC^3D is used to establish the slope model and analyze the stability and displacement of the slope during the steep end-slope mining. Based on the analysis results of different steep end-slope mining slope angles and the slope stability after the inner-dumping, the best tip angle is determined to be 38°. The analysis results show that the mining of other steps will lead to the decrease of slope stability except for 533 m bench; the timely follow-up of the operation of inner-dumping has a significant effect on slope stability. When the inner-dumping reaches to 492 m bench, the safety factor of end-slope reaches to 1.42, it meets the safety demands.