Abstract: Pressure relief technology of large diameter borehole is one of the effective measures to prevent rock burst.Using the method of roadway stress research，the paper analyzes the stress distribution of surrounding rock of large diameter borehole，the mechanism of surrounding rock deformation and fail⁃ ure，and the mechanism of pressure relief and anti-impact. By using numerical analysis method，the effect of pressure relief and anti-scour in soft coal is studied when the parameters of large diameter drilling （drilling distance，drilling length，etc.）are changed. The results show that for soft coal with elastic modu⁃ lus of 0.4 GPa and Poisson's ratio of 0.43，the cracks near the borehole develop quickly，the borehole is easy to collapse，and a large range of fracture zones will be generated during the process of pressure relief. When the variation interval of hole distance is 0.6~2.4 m，better pressure relief effect can be obtained. The peak stress of the surrounding rock is about 9.6 m away from the roadway. When the hole depth is more than 10 m，the pressure relief effect is more obvious. Through the field test，the pressure relief effect of large diameter drilling before and after optimization is compared and analyzed，and it is verified that the pressure relief effect of large diameter drilling after optimization is more significant.

Key words: rock burst, borehole pressure relief technology, large diameter borehole, soft coal, energy dissipation and burst prevention