Abstract: To optimize the structure of three dimensional rotating water jet nozzles, the influence of internal structure of nozzles on the jet effect was simulated by fluent. The characteristics of jet flow field were analyzed when impeller orientation angle is distributed from 15° to 75°; it obtained that the optimum orientation angle is 45°, and the characters of flow field were analyzed when the nozzle was rotated by its axis. The nozzle and matching equipment according the simulation results were tested and experimented in laboratory and field application; the result shows that three dimension rotating water jet enlarging the hole diameter is up to 2.3 times; the pure gas extraction quantity in hundreds of meters drilling is up to 1.79 times of normal drilling; the gas extraction ratio are increased by 79.3% in 59 days, it has better effect for low permeability coal seam.