Abstract: In order to study the overburden hard rock strata affected to the mining stress of the coal mining face, according to the geological conditions of No.7112 coal mining face in Tianchen Mine, a numerical simulation method was applied to study the mining stress variance features of the thick and hard key stratum under the different deposition condition. The study showed that with the sustainable pushing forward of the coal mining face, the support pressure in front of the coal mining face would be increased continuously, but the increased speed would be slow down steadily and the support pressure of the coal mining face would be rapidly reduced after the roof broken down. With the thickness of the thick and hard stratum and the deposition height increased, before the thick and hard key stratum initially broken, the su pport pressure peak in front of the coal mining face would be steadily reduced. The theoretical analysis method was applied to calculate a breaking step of the overburd en key stratum above the coal mining face. According to the study results, the mine pressure bump danger section of No.7112 coal mining could be divided in detail un der the influences of the thick and hard rock stratum. With the implementation of the intensive borehole drillings for the pressure released, the mine pressure bump risk was successully controlled. A safety production of No.7112 coal mining face was realized and could provide the reliable technical parameters to the coal faces around No.7112 coal mining face.