Abstract: In order to study the effect of pressure relief on coal body by hydraulic punching, the high gas geological conditions in Yu Wu Coal Mine are taken as the engineering background, and the research is carried out by the combination of theoretical analysis, indoor experiment and on-site industrial verification. The results show that the process of hydraulic punching mainly through two layers of macro cracks and micro pores to realize the effect of pressure relief to the coal body; the field hydraulic punching effect test shows that the attenuation coefficient of the gas flow in the bore hole is 0.003, only about 1/7~1/8 of the common borehole, and the construction area of the punching measures. The efficiency and effect of drainage are obviously better than that of common drilling area. It is indicated that hydraulic punching technology can effectively improve the drainage efficiency and ensure the safe production of the working face, which is an effective way to solve the problem of pressure relief and permeability enhancement in underground coal seam.