Abstract: The overburden deformation and movement caused by mining may lead the water in the roof break into mine,which threat the production safety of coal mine seriously.Backgrounded in a coalface in Yuyang coal mine area,this paper study how the displacement,stress and fracture in the overlying strata develop by using non-continuous media discrete element program UDEC^2D.According to the study,when coal surface is moving,fissures in the center area of the gob will partially be compacted,while near the open cut and the face,aboundant of fissures lie in the overlying strata,which constitute a class of trapezoidal area with the top of the fissure fracture zone;when the work face is advancing to 140m,the height of fissure area reaches its maximum value,94.5m.The results of this research provide a basis for underwater security.