Abstract: Under the "U" type ventilation condition of the first mining face of the group of close high gassy coal seams, a large number of gas from the adjacent layers poured into the upper corner through the cracks generated by the pressure relief of the coal and rock mass and entered the return air flow, resulting in the gas over limit. Taking the 03X04 mining face of Dongyu coal mine as the research object, the pressure relief gas migration law in the goaf under the "U" type ventilation condition of the mining face was analyzed, so as to determine the belt The "one side and four lanes" combined gas control technical scheme of track trough + high and bottom drainage roadway. The field application results show that the gas extraction rate of the working face has reached 81%, the gas content of this coal seam has decreased by 33%, the net amount of gas extraction from the intercepting boreholes of the side and bottom drainage roadway completely within the pressure relief range has reached 0.02m3/min ~ 0.03m3/min per hole, the maximum gas extraction concentration has reached 90%, and the net amount of gas extraction has increased by more than 2 times, greatly reducing the influx of gas into the working face and the upper corner of the lower adjacent layer, The gas concentration of the return air flow in the track trough and the side bottom drainage roadway of the mining face is stable at 0.2%～0.4%, and the gas concentration in the upper corner is 0.3%～0.4%, which effectively solves the problem that the gas in the upper corner and the return air flow exceeds the limit under the "U" ventilation condition of the mining face, and ensures the safe and efficient production of the mine.