Abstract: In terms of the problem that there is still a shortage in the seepage theory of deep hole water injection at coal mine working face, based on the analysis of coal body stress distribution at working face and its influence on the characteristics of coal seam water injection, the nonlinear seepage equation of coal seam water injection is simplified and solved by using the theory of seepage mechanics, and the time and space evolution law of water injection pressure head, seepage velocity, water injection rate and other parameters are researched by analyzing the characteristics of the solution, additionally, the theory is verified by an engineering example.The coal of the deep water injection section is in the unloading failure area, and the water injection process in this area belongs to the seepage laminar flow.The hydraulic pressure head along the direction of drilling hole has the characteristic of residual error function, and the expansion velocity of the seepage boundary and the water injection rate decreases with the increase of time; while along the direction of drilling depth, with the decrease of coal permeability, the seepage velocity around the borehole gradually decreases, and the wetting degree of the coal is also gradually reduced.