Abstract: To improve sealing effect of horizontal gas extraction borehole in current seam and solve the practical problem of gas extraction for boreholes with easy-failure sealing segment in soft coal mine with high content of gas, through numerical simulation method, the grouting penetration range of the single-fracture grouting method and no-fracture one was analyzed by the COMSOL Multiphysics software. The results show that the main penetration way of grouting is through the fracture surface in the single-fracture grouting method, which makes the slurry fill the fracture in coal well; the grouting technique can inject the seriflux into the fractures existing in coal and rock and make the coal and rock form new structures with high intention and stability, and improve the property and stability of coal and rock. The success of this project contributes to solve the difficulty encountered in high-efficiency dynamic sealing.