Abstract: This paper takes the weak basement of the outside dump of Jiangjun Gobi No.2 Open-pit Coal Mine of Xinjiang Tianchi Energy Company as the research object. Through the routine mechanical experiment and rheological test of the geotechnical soil in the study area, the physical and mechanical indexes of the basement and the abandoned material of the open pit mine are determined. Combined with theoretical analysis, it is determined that the slope landslide mode of the dump is located-shifted and the landslide mechanism is analyzed. The numerical simulation model of the stability analysis of the dump is established, and the deformation and failure modes of the dump slope are simulated. The stability of the dump slope is calculated and analyzed. When the drainage height is 120 m, the potential slip surface penetrates the interior of the dump and the weak basement, and the slope stability coefficient is slightly lower than the safety reserve coefficient.