In view of the problems of short effective contact length, large engineering quantity and low extraction efficiency in the mining of close distance coal seam group, when the overlying roadway is used to pre-drainage the underlying coal seam gas, the traditional floor crossing borehole has the problems of short effective contact length, large engineering quantity and low extraction efficiency. This paper proposes an improved scheme of gas control technology based on directional long borehole in floor. Based on the actual geological conditions of Xiangshan Mine, the fluid-solid coupling model of coal seam gas was constructed by COMSOL multi-physical field analysis and simulation software, and the gas migration law and pressure relief characteristics under two kinds of hole arrangement were quantitatively compared. The simulation results show that the directional long borehole can be arranged along the coal seam for a long distance, forming a continuous strip pressure relief area, which greatly increases the effective extraction length of the coal seam section and effectively eliminates the blind area of inter-layer extraction. The field industrial test shows that the improvement effect of this technology is remarkable. The gas extraction concentration of the directional long borehole in the floor is as high as 76% at the initial stage, and the average is maintained at more than 20%, which is significantly better than the traditional borehole. The average single-hole gas extraction purity is about 4.0 m3/min, which is about 2 times that of the traditional process, and the high concentration maintenance period is significantly prolonged. While greatly reducing the amount of drilling construction, this process has realized the cost reduction, efficiency increase and fine management of gas control in underlying coal seams.