Abstract: There is gas outflow from the Y-type ventilation "two-in-one-return" working face and the tailing lane of the mining area, which could result to disasters such as gas explosions induced by gas overloading. This paper takes Shanxi Dongrui coal mine working face of gob-side entry retaining as the research object. Fluent numerical simulation software was applied to simulate the basic law of gas transport of gob-side entry retaining Y-type ventilation. The influence of different ventilation conditions on the distribution of gas concentration was analyzed. The results show that: increasing the air volume of the transportation roadway reduces the gas concentration along the open roadway, and increasing the air volume of the auxiliary transportation roadway reduces the gas concentration in the working face. As the total air volume is constant, changing the air distribution ratio of the two inlet roadways has a greater impact on the gas concentration in the working face. The impact on the air mining area is relatively small. Increment of the advancement progress of the coal mining face, the difficulty of gas management retaining lanes and the working face rises. The optimal ratio of ventilation moved from the transportation lanes to the auxiliary transportation lanes. In the process of mining, the ratio of air volume in the inlet road to prevent the gas concentration in the working face and the tailing road from increasingshould be constantly adjusted. Improvement of the degree of airtightness of the gob area by regulating the air quantity to prevent the gas accumulation.