Abstract: In order to effectively conduct pressure relief on coal seams under key layer control conditions, and improve the penetration rate and gas extraction efficiency of coal seams, this article takes the situation of the N3301 coal seam in Gucheng Mine, Shanxi Province as the engineering background, and based on key layer theory and breaking distance theory, the key layers of the overlying rock strata of the coal seam are analyzed, calculated, and identified. Combined with the geological conditions and geostress distribution status of coal rock strata, the stress and energy spatial field changes of the rock mass during the joint pressure relief process of the main and sub key layers are analyzed by FLAC^3D simulation. The results show that after key layer hydraulic fracturing and implementing 3D gas governance technology of large aperture cavity formation with a diameter of 400 mm in the coal seam, the gas extraction effect is significantly improved, and can effectively conduct pressure relief and permeability enhancement on the coal seam. For ordinary boreholes, the gas extraction volume fraction is improved by 40%, and the gas extraction pure quantity is improved by 7.64 times; For cavity forming boreholes, the gas extraction volume fraction is improved by 21%, and the gas extraction pure quantity is improved by 1.6 times.