Abstract: Based on a deep coal mining in south of Hedong Coalfield, by the methods of indoor similar simulation and on-site investigation, the paper studies the second surface subsidence caused by the upper coal mining under conditions of deep mine. After the compaction of strata, with the mining of lower coal, the overburnden has a larger deform after secondary mining because of the deep occurrence. By observations, abscission layers at the top of the goaf and near the surface is appeared, and two larger tilt layers are at the boundary of the model. The surface have obvious secondary sinking,which is a completely subsidence basin.