Abstract: Aiming at the problems of natural disasters such as landslide and ground fissure caused by mining in loess gully area, based on the mining geological conditions of Hanjiawan Coal Mine, we sorted out the monitoring data of the surface observation points in the mining area. The surface monitoring results show that the working face generally experiences start-up period, active period and decline period from mining to stop. In the initial stage of mining, the surface movement and deformation of the mining area are not obvious; when the advancing distance of 12106 working face is between 13 m and 109 m, the surface movement and deformation change dramatically, and the maximum subsidence can reach 1 963 mm, which is easy to cause landslide disaster. At the same time, the physical and mechanical parameters of the rock mass of the slope of Hanjiawan Coal Mine were selected. The FLAC^3D software was used to simulate the formation mechanism of surface landslide hazard under different slope angles. The overlying strata structure is destroyed due to the mining of working face, the whole subsidence basin is shifted to the center, and the slope is subjected to tensile and compression deformation, resulting in plastic failure. The results show that when the slope inclination angle is greater than 60°, the displacement of the slope is not uniform, and the rock layer with large displacement loses support, resulting in landslide disaster; when it is less than 30°, the slip surface of the bedrock surface develops to the surface, and the occurrence of landslide disaster is less likely.