Abstract: Abstract: Mining cause activation of faults, fault activation lead to mine water inrush accident occurred by containing the artesian aquifer water, this paper study water inrush mechanism ,using finite difference numerical simulation software FLAC3D simulation and analysis stress field and plastic zone in different fault dip. The results show that the dip angle is bigger, fault plane shearing force and stress the more; mining deep fault activation range greater than shallow fault activation range; small angle normal faults produced fracture more easily through in the face of the bottom plate. By using the software, the simulation of stress field and plastic zone near the fault in the near fault mining area will help to determine the setting width of the fault waterproof coal pillar and the prevention of the occurrence of mine water inrush accident. Key words：fault; geostatic stress; numerical simulation; FLAC3D