The mechanism of mine water inrushes in coal mines in China differs considerably from that in other countries. In China, most water inrushes occur from floor strata, where the water-inrush sources are karstic limestone aquifers. Our study describes the mechanism of mine water inrushes through a fault in the mine floor using principles of strata mechanics and the path of water inrush from an aquifer to the working face. A criterion to judge whether a ground water inrush will occur through a fault or not is also described, together with a case history of water inflow in the Feicheng coalfield, China.