Abstract: Taking the Henggou Coalfield as the research object, the water filling sources and water conduction channels of coal seam floor water inrush were systematically analyzed by means of hydrogeological analysis and hydrochemical testing. Through the analysis of isotopic ratio characteristics and spatial distribution of hydrochemical parameters, the recharge relationship between surface water and confined aquifers was revealed. It is clarified that the Taiyuan Formation and Ordovician aquifers are the main water inrush sources of the S coal seam floor, and the influences of structural factors such as faults, collapse columns and poorly sealed boreholes on water inrush channels were determined, providing key geological basis for water inrush risk assessment. Meanwhile, a combined weighting model based on the improved analytic hierarchy process (IAHP), entropy weight method (EWM) and relative entropy theory (Kullback-Leibler divergence) is proposed. This method optimizes subjective weight distribution via the product scale method, combines the objective data characteristics of the entropy weight method, and introduces relative entropy theory to construct an objective function for solving the optimal combined weight. The model effectively balances expert experience and data objectivity, improving the coordination of weight distribution and the reliability of evaluation results. Combining the combined weights with the vulnerability index method and GIS spatial interpolation technology, the water inrush vulnerability zoning map of the S coal seam floor under the influence of the Taiyuan Formation and Ordovician aquifers was compiled. The results show that the water inrush risk of the S coal seam floor presents significant spatial heterogeneity: the northern part of the coal seam is mainly classified as vulnerable zone, most of the southern and central parts as transition zone, and the southeastern part as relatively safe to safe zone. Most of the previously mined areas have low water inrush risk. However, affected by the Taiyuan Formation and Ordovician aquifers, more than 80% of the area (transition zone and above) is threatened by water inrush to varying degrees.