Abstract: To solve the problem of gas over-limit in upper corner of fully-mechanized mining face with high gas outburst, based on 12507 working face of Tunlan Mine, this paper discusses the theoretical basis and engineering application scheme of gas extraction from the large-aperture working face, from the perspectives of gas source in fully mechanized mining face, gas occurrence in goaf area, arrangement of high hole and construction of borehole sealing. Through field engineering test, the test data from a distance of mining face is selected to analyze, and the results show that the strike high hole with an aperture of 215 mm is located in the roof of coal seam 12 to 30 m and horizontal offset distance away air return gateway 17 m; under the condition of 18 m depth of polyurethane sealing hole, the average concentration of gas extraction from borehole reaches above 80% and the pure quantity of gas extraction exceeds 6 m³/min; during the mining period, the gas concentration in the upper corner fluctuates steadily around 0.4%, and its maximum value is less than 1%.