Based on large gas liberation of 己_15-17-12041 recovery working face goaf in Pingbao Mining Industry inducing the large gas concentration in working face upper corner and return air, low position roadway large aperture borehole was adopted to reduce the gas in goaf, a 90° elbow faced with goaf at air return drift roadway drill end was installed, effect of drainage negative pressure was used to transport the working face goaf gas from upper corner to deep goaf. The control theory changed from blocking to discharge. The gas concentration in upper corner and at air return drift tunnel was from 0.56% ~ 0.86%, 0.4% ~ 0.75% to 0.18% ~ 0.34%, 0.05% ~ 0.17%. The effect was very significant, and it eliminated the threat of gas concentration overrun.