Abstract: Aiming at the problems of low comprehensive efficiency and high treatment cost in the conventional treatment of mining pressure relief gas in “U” ventilation mining face, taking a mining face in Jincheng Mining Area, Shanxi Province as the research object, ϕ200 mm large diameter high-position directional borehole for gas control of mining pressure relief is proposed. Based on the analysis of the technical difficulty of large-diameter high-position directional borehole in the roof of the coal mine, the key drilling equipment are selected, including ZDY20000LD directional drilling rig, BLY460 mud pump truck and multi-power expanding drilling tool. The combined strong slag-discharge directional drilling technology and multi-dynamic single-reaming technology have been developed to realize directional drilling of ϕ120 mm high hole and single-reaming of ϕ200 mm hole under complex formation conditions, the comprehensive drilling efficiency is more than 50% higher than that of conventional multi-stage expanding. The gas drainage effect shows that the area of 30-40 m away from the roof and 40 m away from the return air roadway is the mining fracture intensive development area. The average gas drainage concentration in the borehole is maintained at more than 40% and the maximum pure amount of gas drainage is 10.94 m³/min, which has remarkable effect.