The roof of 15 coal seam under mining in Maijie Coal Industry is relatively hard, and the mining roadway needs to be supported by 30 m coal pillar. In order to reduce the deformation of the roadway and the reserved amount of coal pillar, the roof cutting and pressure relief of the mining roadway are decided. Combined with the geological conditions of 150505 fully mechanized caving face, the parameters and construction technology of roof cutting were designed. Through numerical simulation, it can be found that when the roof cutting height is 17 m, the hard roof of coal seam is completely cut off, and the stress around the small coal pillar roadway is significantly reduced, which can provide certain reference for the roof cutting and pressure relief design of fully mechanized caving face.