Abstract: In order to solve the problem that quantitative evaluation of influence degree of factors affecting water inrush from coal floor, we present a new method: dimensionless information fusion, which based on multi-source information complex. To take the Nantun coal mine for example, we have a detailed analysis on the hydrogeological data of the coal mine and evaluaton of factors affecting water inrush from floor. We also evaluate the water inrush risk in lower group of coal seams mining. We have quantitative evaluation of factors affecting water inrush from floor by dimensionless information fusion and the influence degree is determined. The evaluation results provids the powerful foundation for evaluation of water inrush risk from coal floor in lower group of coal seams mining in Nantun coal mine and has important guiding significance to evaluate the water inrush risk from floor to other coal mines.