Abstract: In order to analyze the influence degree of different factors on gas drainage effect,which can help to reasonably determine the gas drainage scheme,the influencing factors of gas drainage efficiency were summarized in this paper.The mathematical model was established on the basis of measured data of the gas parameters and drillhole parameters in 3^# coal seam of Beizhuang coal mine in Yangcheng,the relationship between drainage and drainage time,gas permeability of coal seam,drillhole spacing,drillhole aperture and negative pressure of drainage was analyzed by computer numerical simulation.The result showed：the key to increase the gas drainage is to increase the permeability of coal seam；under the condition that the permeability of the coal seam is invariable,measures such as ensuring sufficient drainage time,increasing drilling density,increasing drillhole diameter properly,raising negative pressure of drainage can be adopted in gas drainage to achieve the desired results.