With the continuous increase of mine mining depth, floor water inrush has become one of the important disasters affecting the safety of coal mine production. No. 15 coal seam of Xinjing Mine was taken as the research object, combining with the mine geological conditions, the risk of water inrush of No. 15 coal seam was evaluated by using "five graph-double coefficient method". Taking the "pressure coefficient" as the main evaluation index, combining with the "water inrush coefficient" evaluation index and "three-level discrimination", the evaluation standard was determined. No. 15 coal seam of theoretic analysis calculation with pressure coefficient between 0.0121~ 0.0380 MPa/m, the water inrush coefficient between 0.0179 ~ 0.0665 MPa/m, with coal seam mining field area Ⅱ level evaluation, the other areas Ⅰ level evaluation, the results of under pressure mining of No. 15 coal seam provided guidance significance.