Based on analysis of water inrush coefficients developed and applied in deep coal mining with high water pressure, the author proposes that there are some defects of water inrush coefficients in calculation and application. By simulation experiments on the water resistance properties of the aquiclude in a coal seam floor, the author arrived at the distribution and digital characteristics of residual pressure in the course of high-pressure water rising in the water-resisting floor. The formula for a water inrush coefficient has been further revised.