Abstract: This paper is based on a hydraulic borehole flushing simulation using self-developed multi-field coupling testing system for coal-bed methane （ＣＢＭ） and simulation test system for high-pressure rotating water jet under different rotating speed of the bore bit. We discuss the amount of flushed out coal under different situations, the appearance of the borehole and the dynamic evolving pattern of the parameters such as gas pressure and gas flow during the whole experiment. The results show that: the appearance of the borehole by hydraulic flush is larger, the section approximates to a circle with cracks on its surface. Meanwhile, with the increase of the punching speed, it appears that the amount of flushed out coal as well as the equivalent radius after flushing have also increased as a whole; various gas drainage observation locations have shown a greater drop of the gas pressure after flushing with greater gas flow, thus, the effect of pressure relief and permeability enhancement is obvious.