Abstract: Due to high gas content and poor gas permeability in No.2 coal seam of Xuehu Coal Mine, coal seam gas is treated by borehole along the bed, which has problems such as poor gas drainage effect and long time to reach standard. For the above problems, an ultra-high pressure hydraulic slotting technology was applied to borehole gas drainage of the coal seam. Single-factor test was carried out to determine optimum process parameters of ultra-high pressure hydraulic slotting applicable to the No.2 coal seam of Xuehu Coal Mine: slotting pressure is 60-70 MPa, slotting time is 25 min, slotting speed is 80 r/min and slotting spacing is 2 m. After field application of ultra-high pressure hydraulic slotting technology with the optimized process parameters, average daily gas drainage volume fraction of slotting borehole is about 1.75 times that of ordinary borehole, average daily gas drainage pure volume is 3.25 times, time of gas drainage to reach standard is shortened by about 42% and residual gas content is small.