Abstract: The sealing quality of extraction drilling holes is closely related to the grouting pressure. In order to study the sealing quality of each bedding borehole under different grouting pressures, the 2214 working face of Liujialiang coal mine of Xuangang Coal Power Co., Ltd. was taken as the test object. First, according to the actual occurrence of the coal seam, COMSOL numerical simulation software was used to simulate the diffusion range of slurry in the coal seam under different grouting pressures. The results show that within the range of 1-4MPa grouting pressure, The diffusion radius of the slurry in the coal seam is positively related to the grouting pressure, while the increase of the diffusion radius of the slurry is inversely related to the grouting pressure; Secondly, under the condition that the initial sealing depth, sealing length and other sealing parameters are fixed, the on-site borehole sealing test is conducted according to the four grades of 1MPa, 2MPa, 3MPa and 4MPa, and the sealing quality of each extraction borehole is evaluated and compared by using the air leakage rate. The field test shows that there are 4 and 2 drill holes with 1MPa and 2MPa grouting pressure, and the average air leakage rate is 32.76% and 28.65% respectively, while there is no air leakage in the drill holes with 3MPa and 4MPa grouting pressure; The numerical simulation and field test results show that the reasonable grouting pressure is 3Mpa when drilling and sealing holes along the working face.