Abstract: In order to correctly judge the air flow direction in goaf of the working face with "one inlet and two return" ventilation, and guide the mine to strengthen the management of gas drainage in goaf, taking 1604 fully mechanized top coal caving face of Guhanshan Coal Mine as the research object, by releasing SF₆ gas at the lower coal wall of the open-off cut in the working face and the outer section of gob-side entry retaining, the air leakage and gas emission law of the working face were analyzed and determined. Combined with the change of ventilation resistance and the measurement results of air volume, the dynamic change process of air leakage in goaf with the advance of working face was analyzed. The results show that, the air flow of the working face leaks into the goaf from the upper side of gob-side entry retaining and the lower part of the open-off cut, and flows into the working face from the upper part of the open-off cut, and the total air leakage in the initial period of gob-side entry retaining accounts for about 15% of the air intake; the air leakage of gob-side entry retaining increases the gas emission amount and emission range of goaf, the amount of gas emission from the goaf accounts for 75% of the total gas emission during the maintenance of the working face; the air leakage channel along the gob-side entry retaining increases with the advance of the working face, but the air leakage reaches the peak before the first pressure in gob-side entry retaining, and then affected by the change of roadway air flow resistance, the sub air volume and air leakage in gob-side entry retaining show a slow downward trend.