The floor Karst water always threatens coal mining of the North-China type coalfields. In recent years great breakthroughs have been made in the study of the mechanism of the water inrush. It is believed that karst fissure networks are the basis for the water inrush, the lithomechanical characteristics and thickness of the aquicludes are the restricting factors, faults are the key element and the coal mining activity is an inducing factor. In the protection of water inrush, techniques, such as drainage to lower water pressure, injection of mud into aquifers and damming water with curtains, have been used successively. This paper introduces the status quo of protection and measures against inundation, which may provide guidance for harnessing the inundation in coal mines.