Coal seam water injection is to inject pressure water and aqueous solution into coal through drilling holes to increase water content, thus changing the physical and mechanical properties of coal, reducing the generation of coal dust, and also reducing rock burst, coal and coalbed methane outburst and spontaneous combustion.

Coal seam water injection is divided into deep hole water injection and shallow hole water injection according to drilling depth.

Deep-hole water injection is to drill holes in the air inlet lane or air return lane in front of the working face along the inclined coal seam parallel to the working face. The hole depth is generally 2/3 of the inclined length of the working face, and the hole diameter is 75 ~100 mm. After sealing the hole with cement slurry or rubber hole sealing agent, water injection can be started. Compared with shallow-hole water injection, deep-hole water injection is more expensive and more difficult to drill, which is only suitable for medium-thick coal seams. The advantages are large pre-wetting range, full wetting and no influence on coal mining. However, in some mining areas, because the coal seam is not destroyed, water injection is difficult and the water injection amount is small.