Abstract: Gas extraction borehole is affected by negative pressure fluctuation, the coal (rock) around the borehole has a loosening effect, and the sealing quality gradually decreases with the extension of extraction time, which restricts the gas extraction effect. In order to improve the quality of borehole sealing and realize the dynamic pressure retaining effect of borehole sealing device, the water sealing equipment for mining is designed. The hole sealing and pressure maintaining device consists of a capsule hole sealing device, a water injection check valve and a testing device. The results of similar simulation experiments show that friction increases with the increase of gas injection pressure. The larger the diameter of the hole packer, the more significant the increase of friction. The field application effect is remarkable.