Abstract: In order to promote the pre-extraction of gas in low permeability coal seam and eliminate the risk of coal and gas outburst, high pressure jet punching and hydraulic flushing measures were adopted. Firstly, the coal permeability evolution model of high pressure jet punching and hydraulic flushing process was constructed. Then the evolution of coal permeability and the rule of gas movement in coal after punching were obtained by calculating, that was, the radius of permeability enhanced area of coal around the borehole increases linearly with the increase of borehole radius. The in-situ test of hydraulic flushing carried out in Xinjing Mine shows that:compared with the direct pre-extraction of coal seam gas, high pressure jet punching and hydraulic flushing combined with gas drainage measures can save the amount of drilling and enhance the gas drainage effect. Moreover, it is more effective to eliminate the outburst risk during the excavation process, improve the tunneling speed of roadway, and ensure the safety of mine production.