In order to accurately predict the risk of water breakout at the bottom of coal seams, the "five diagrams - two coefficients three-stage discrimination method" was used to evaluate the risk of water breakout at the bottom of coal seam No. 15 coal seam by analyzing the depth of damage, the thickness of the protective layer, the distribution of head and the thickness of the effective protective layer based on the hydrogeological conditions of the region and the coal field. The risk of bursting water in the bottom plate of No.15 coal seam was evaluated by zoning to prevent the occurrence of bursting water at the floor.