Bulianta coal mine is the world's largest single-well underground mine, forming a large number of irregular goaf, mining 1-2 coal will be greatly affected by its overlying goaf, the mine pressure in and out of the goaf is severe, the shrinkage under the movable pillar is large, even the support topples, crushing and so on. Therefore, in order to reduce the occurrence of such disasters, the experimental mining face of No. 1-2 coal 12415 across the Goaf of No. 11401 which overlying distance is only 7.9 m is taken as the experimental mining face, the evolution characteristics of plastic zone and surrounding rock stress field are analyzed by using numerical simulation method when the down-going short-distance coal seam is mined into, across and out of the overlying mined-out area, the source of strong ground pressure phenomenon caused by mined-out area is explored, which provides a reference for the proposal of disaster prevention in continuous mining face.