In order to improve the efficiency of pressure relief gas extraction by high-level directional drilling in the roof of No.9 coal seam in Luotuoshan Coal Mine, Inner Mongolia, and realize safe and efficient gas extraction, based on the engineering geological information of the coal mine, a three-dimensional numerical model was established by using the discrete element software 3DEC, and the evolution law of the development height of the overburden fracture zone of No.9 coal seam with the advancing distance of the working face was analyzed. Then, the goaf model was established by COMSOL to study the gas migration law of goaf and working face under different advancing distances. Finally, the influence of drilling extraction layer, drilling number, drilling spacing and other factors on the gas distribution in the goaf of high-level drilling extraction is studied. The results show that the shape of the fracture area of the overlying strata of the coal seam is similar to the shape of the ' ladder-like ', and the final fracture zone development height is about 80 m. When the horizontal position of the high-level borehole is 30 m, the vertical position is 30 m, the number of boreholes is 3, and the spacing is 8 m, the extraction effect is the best. The research results provide a theoretical basis for further efficient extraction of pressure relief gas in the coal mine.