Abstract: Fluent software is used to carry out numerical simulation of air leakage and gas migration in goaf with different tail gateway’s air volume in 8103 “J”-type ventilation working face of Wangzhuang Coal Mine to obtain the distribution of air leakage along the whole length of working face and the gas distribution in goaf, whose variation laws with the tail gateway’s air volume are also analyzed. The results show that when the total air volume is constant, the whole airflow of different tail gateway’s air volume is leaked from working face to goaf, and air leakage in the lower corner is the most. With the increase of tail gateway’s air volume, the air leakage gradually increases, and the increase in lower corner and return airway area is larger; high concentration gas has a tendency of moving to the deep of the goaf.