Abstract: In the exploitation process of coal seam group, the exploitation of the mining seam will make stress redistribution in the rock of coal mining face and the adsorption state of adjacent coal seam gas discharge pressure and desorption. Meanwhile, cracks were formed along with the movement and breaking of rocks in the overlying, and a large amount of gas inflow into the working face. In order to avoid gas overrunning at working face, by researching the break laws of overlying rock, combined with situation of gas drainage, we optimized the original gas drainage system, and the gas concentration was increased by 21.2%, and the exhausting methane of face ventilation was reduced by 18.33% after the optimization, the safety is greatly increased.