Abstract: The reserves of steeply inclined thick coal seams by horizontal slicing method are relatively abundant in our contry. This method has low production cost, good safety, high efficiency, but stress concentration degree is high around the stope, which leads to strong strata behaviors. Therefore, numerical model for the mining of steeply inclined thick coal seam is established through FLAC^3D; we simulate the stress distribution in the process of mining, and analyze the influence of stress distribution law and slicing on lower layered pressure relief. Simulation studies show that the range of the abutment pressure increase is leveling off with the working face advancing, and forming obvious stress area; the coal and rock pressure relief range of the upper goaf increases with the increase of mining layers at the same time.