Through investigating some coal mine water injection pressure of different coal structures and different injection time factors, such as changes under the condition of coal seam water injection test，comparative analysis of different excavation working face, the same heading face of coal injection effect，it showed that main factors affected the coal seam water injection were development degree of the fractures and pores in coal, pressure overburden and support pressure, injection parameters, gas pressure and coal seam in the liquid properties. Analyzing factors that influenced water injection improved effect of coal seam injection and provided guidance.