Abstract: Choosing Anjialing Mine as research object, the whole process of strata failure and deformation of slope in underground mining is simulated by continuum based discrete element method (CDEM). The analysis of vertical stress in the overlying strata shows that the height of bending zone is half of the total height of collapse zone and fracture zone. The first roof caving distance in the undergrounding mining is 115 to 156 m in this simulation. The upper slope collapsing to the mine goaf and the tension crack in the open-pit slope were obtained when the mine goaf area was extending to the area that is just under the open-pit slope. The deformation and failure of open-pit slope is mostly interlay movement with collapsing to the mine goaf in the caving simulation. The underground mining can not cause the whole landslide directly. The pressure foot project can effectively reduce the slope movement collapsing to the open-pit mine along the interface by comparison of numerical tests.