Abstract: In this paper, we discussed the mathematical model of gas extraction drilling and studied the mathematical model of plane radial stable seepage and radial unsteady seepage during drilling gas extraction. Taking the gas extraction of Dahuangshan Coal Mine as the background and through beds hole as an example, we use COMSOL Multiphysics software to simulate the gas flow pattern near the drillings under different extraction time(15、30、45 d) and different apertures (94、180、300 mm). Thus, the gas velocity field and gas pressure distribution and the pressure contour are obtained. Simulation results are analyzed to determine a reasonable gas drainage borehole diameter and extraction time.