Abstract: We introduce the steps of polyurethane-cement paste hole sealing method, analyze the problems of this method in sealing process when the downward through beds pressure hole connects with the fracture containing water, and improve the original method to solve these problems. Using sealing bags packaging modified polyurethane to replace a towel wrapped polyurethane as the plug material, we develop a simple grouting pump powered by compressed air, inject the cement paste from the bottom of the drilling so as to pile out of the water in the borehole from the orifice. In addition to the piezometric pipe, we add a drainpipe to the testing room, which is used for piling out the water in the testing room powered by compressed air. This method is applied to the gas pressure measurement at the north wing 12 mining area of Wangxingzhuang Coal Mine, which successfully measures the gas pressure of the specified coal seam.