In this paper, the problem of gas extraction in coal mine is studied. Taking the 6302 working face in the east well area of Sihe mine as the object, the effective extraction radius of borehole is determined by analyzing the geological conditions and gas distribution of coal seam and combining with numerical simulation. The gas reserve method was used to determine the layout of the extraction boreholes, and the COMSOL software was used to simulate the extraction effects of different diameter boreholes. Finally, the optimal borehole diameter was determined to be 94 mm. The mathematical model of the number of days to reach the standard and the effective extraction radius is established. Through the comparative analysis of the extraction effect of ordinary boreholes and directional long boreholes, it is found that the effect of the two is similar under the same conditions. This study provides scientific technical support and decision-making reference for coal mine gas extraction.