An important part of open-pit mining is the waste dump, where the topsoil and rocks extracted during open-pit excavation are discharged, mainly including the upper waste material and the base that carries the waste material below. Most of the external dumping sites are directly dumped on the initial surface, occupying a large area. According to the survey, the area of soil dumping sites in mining sites in countries such as the United States and Russia has reached more than half of the total mining area. This article takes the waste dump in the Dongbang area of a mine in Shanxi Province as the research object. Through numerical calculations and similar simulation methods such as friction experiments, it was found that the stability of the slopes below the 1290 step and the 1260 platform on the south side of the eastern slope of the waste dump is poor. The single step is relatively high and mainly composed of silty clay, which is compacted and prone to cracking and sliding when exposed to water. The overall stability of the slope is basically stable, and as the soil is discharged, the height of the slope increases, and supervision needs to be strengthened. If necessary, gaps should be sealed. The stability problem of slopes is still serious, and the mechanism of slope failure needs to be studied.