Abstract: Underground water may change the mechanics qualities and stress state of the cover rocks on the coal-mined bed,aggravating environmental hazards induced by coal mining such as deformation,subsidence,crevasse of the ground and loss of water resource.During environmental hazards induced by coal mining result in the fracture of water-lock rock layers and the change of the motion system of underground water so that cause mine flood and deterioration of ground environment.Interaction of the both factors makes for happening and developing of environmental hazards induced by coal mining.Therefore,underground water is an important factor,which cannot be ignored in studying environmental hazards induced by coal mining