Abstract: The geological environment conditions in Southwest of China are complex, and most of there develop binary mountain structures which are top hard-bottom soft and top steep-bottom gentle. Frequent underground mining activities can easily lead to collapse and landslide disaster, so the research on such collapse and landslide disasters is imminent. This paper took Panzhihua coal mine collapse as an example as well as summarized the deformation and destruction characteristics of the collapse body. Meanwhile, simulated the deformation trend, mechanical behavior, fracture evolution process and geological destruction mode of the slope and overlying rock mass under the action of underground mining based on PFC^2D software. The results of research suggest that the stress concentration effect of goaf boundary is significant under the action of underground mining, which leads to the first development for fractures, and the stress adjustment shows arch stress distribution. The shear stress at the slope toe is concentrated and has obvious swell phenomenon. The displacement and contact force increment of the slope top are slower than the slope toe, the deformation and stress transfer have obvious time lag effect. The displacement and fracture range increase with the augment of underground mining area, in addition, always deflect towards the slope surface. For the soft-hard interbedded rock mass between the slope toe to the second section of the Yongningzhen Formation, the deformation modes are plastic extrusion of soft rock, fracture destruction of hard rock, overall bend and sink as well as topple to the free direction, the slope top is mainly cantilever bend and fracture. The geomechanical model of the slope can generalize four stages:"supergene" transformation, plastic flow-tensile, bend-tensile and collapse.