Abstract: in order to increase the permeability of the coal seam, improve the gas drainage efficiency of the coal seam, and ensure the safety production of the working face, the ultra-high pressure hydraulic fracturing scheme of n3704 siwasi roadway (under) crossing layer was studied and designed, and the fracturing effect was preliminarily investigated. The results show that through the coalbed fracturing in No.7 coal seam, the pure gas drainage efficiency after fracturing is increased by more than 10 times, the coal seam is changed from difficult to drainage coal seam and drainage coal seam to easy drainage coal seam, and the coal seam permeability coefficient is increased by more than 50 times; at the same time, under the condition of 750m buried depth and water volume of 109.72m3, the drainage radius after fracturing can reach 50~70m, which is improved Gas drainage efficiency can improve the passive situation which is not conducive to production due to gas restriction.