In order to solve the poor application effect of borehole gas extraction in coal seam with high gas content and poor permeability, taking 3104 working face of Zhongxing Coal Industry as the research object, the application technology of large diameter borehole gas extraction in large soft and outburst coal seam is studied. By setting 25 groups of large-diameter gas extraction boreholes with a diameter of 300 mm in the underground, and comparing the extraction effects with 60 small-sized extraction boreholes with different diameters, the results show that the average gas extraction amount of large-diameter gas extraction boreholes is more than 4.39 times that of small-diameter gas extraction, which significantly improves the underground gas extraction effect.