Abstract: In order to effectively solve the problem of large alleyway deformation under the condition of coal mines, based on the comprehensive mining surface of Mining 15201as the research object, analyzed the law of covering the rock layer on the top of the thick top board, and determined the cutting of the top -cutting process as the main aspect. Based on this, the 3DEC numerical simulation software is used to optimize the analysis of the two parameters of the cut -top angle and the top height of the cutting height, and the optimal cut -top angle and the height of the top are 15 ° and 8m, respectively. The implementation effect of the cutting technology process of the top -cut pressure relief technology has effectively blocked the stress accumulation and transmission process of the rock layer on the empty area, and improved the overall stability of the lane siege rock. Within the range, the work surface is safely recovered.