Abstract: In order to solve the problems of poor effect of pressure relief and anti-reflection of hydraulic slotting and difficulty of coal cinder discharge in slotting borehole in soft coal seam, the research on process parameters of hydraulic slotting in soft coal seam was carried out. On the basis of studying the main controlling factors of hydraulic slotting in soft coal seam, the influence of different hydraulic slotting process parameters on pressure relief and anti-reflection effect of slotting coal seam and borehole gas drainage was analyzed; the best hydraulic slotting process parameters of soft coal seam were obtained through field investigation of gas drainage effect of hydraulic slotting under different process parameters and borehole slotting coal production data. The optimal combination of hydraulic slotting parameters was applied in the field. The test results show that the slotting pressure, hydraulic cutting width and cutting drill pipe rotation speed are the main control factors affecting the hydraulic cutting pressure relief effect in soft coal seam. After the process optimization, the average drainage pure quantity and average methane volume fraction of the slotting borehole are increased by 2.58 times and 0.58 times respectively.