Abstract: According to the characteristics of big gas content and bad air permeability at single coal seam of jiulishan Coal Mine, using crossing layer hole to implement hydraulic flushing and increase air permeability technology, after hydraulic flushing, the gas concentration increases 2.4 times, gas flow increases 7 times, effective drainage aperture becomes 5.2 times of original aperture, these can obviously improve the gas drainage efficiency. Combined with the actual situation of 15071 floor suction roadway, hydraulic flushing pressure, effective time and other technical parameters are optimized, effective influence radius of hydraulic flushing hole is 4~5 m by using the parameters such as pressure changes.