Abstract: The flushing shape is simplified to a cylinder with a diameter of 0.7 m, according to the statistics of coal output by hydraulic flushing technology in the Sijiazhuang Mine, and a fluid solid coupling mechanics model by using simulation software of COMSOL Multiphysics based on elastic mechanics and gas flow theory is built to analysis the effective radius of gas drainage and the appropriate spacing of holes. It has been verified by field inspection, the simulation results are basically consistent with the field measurements, it illustrates that the hydraulic flushing gas extraction parameters can be simulated by simplified form of flushing combining fluid-solid coupling mechanics model to provide convenient.