Abstract: Sealing technology and sealing parameters are the key factors that restrict the effect of drilling gas extraction, the basic principle of the sealing location and sealing pressure of gas drainage borehole are given by analyzing the distribution characteristics of stress and cracks in the surrounding rock of roadways and boreholes. Combining with the defect of “triangular area” of slurry leakage in the “two plugging and one injection” sealing device, a new type of pressure maintaining grouting sealing device is designed, which integrates the grouting pipe, the grout return pipe and the gas drainage pipe to improve the air tightness and grouting pressure of the sealed bag. Field industrial experiments show that compared with traditional polyurethane and the “two plugs and one injection” sealing process, the gas extraction concentration increased by 32.98% and 11.94%, and the gas extraction volume increased by 47.1% and 19.05%, respectively, after 30 days of borehole pumping. After 60 days of borehole pumping, the extraction concentration was increased by 105.96% and 50.30%, and the gas extraction volume was increased by 120.0% and 37.5%, respectively.