Abstract: In order to study the gas drainage seepage law of the borehole and to provide the basis to the rational layout of the boreholes, in consideration of the ga s-water two-phase flow, a fluid-solid coupling model of the gas drainage was provided.Based on the effective stress principle of the multi pore medium and in considerat ion of the stress occurred by the gas adsorption and desorption, a coal stress-strain relationship was derived.A gas-water two-phase flow process of the water and gas migration was analyzed.Based on the relative permeability as the bridge, a water seepage equation was provided and the gas seepage equation of the Klinkenberg effe ct was considered.A dynamic evolution of the seam pore rate and permeability was established as the coupling terms and a numerical simulation was conducted on No. 4321 coal mining face in Chengzhuang Mine. The results showed that, it is reasonable to set the pre-drainage period of gas drainage in No.4321 bottom tunnel through t he borehole for 90 days.During the gas drainage process, the gas sewage velocity would have stages and the gas drainage negative pressure increased would not hav e obvious influences to the gas drainage effect. The layout mode of the borehole passed through strata would have the borehole completed space of 9 m and the drilling site space would be 9 m.The engineering practices showed that the measured gas pressure variation condition of the seam was basically fitted to the numerical simulati on results and the gas content of the seam was 6.46 ~ 7.67 m3/t after the gas drainage completed. The gas density from No.43212 gateway was reduced by 37% and th e gas drainage effect was excellent.