Abstract: Coal seam water injection is one of the most active and effective measures to reduce the coal dust generation. In order to improve the effect of coal seam water injection, according to the principle of compound wetting agent, it selected five different types of surface-active agent and a neutral inorganic salt to compound, and obtained five wetting agents with different components. It used capillary rise method to measure the surface tension of wetting agent under different concentrations, and obtained the lowest surface tension and the critical micelle concentration of five wetting agents. By contrast, the wetting agent A had comprehensive excellent performance. Then it selected coal samples in two different regions, with HARKE-SPCA contact angle measuring instrument, it measured the contact angle of pure water and wetting agent A solution on the surface of coal samples. The practice had proved that the contact angle of wetting agent A solution was much smaller than pure water on the surface of coal samples, it could effectively reduce the surface tension of pure water, and improve wetting effect of pure water on the coal.