Abstract: In order to study the influence of water injection pressure on the wetting radius of coal seam and provide references for the selection of water injection parameters in coal seam water injection technology, the distribution of pore water pressure and pore water seepage velocity under different water injection pressure of coal seam was numerically simulated by Comsol software.The results showed that during the process of water injection, the general distribution of pore water pressure around the borehole is decreasing to the surroundings in an elliptical shape with taking the drilling as the axis; the seepage velocity of pore water is the maximum near the water inlet and smaller around the pore wall, the diffusion decreases to all around from the water inlet. The exponential function relation between different water injection pressure and wetting radius of coal seam is fitted by using simulation data.