Abstract: The paper introduces the method by wich the water inrush mechanism is studied with the physical analog simulation technique. The experiments indicate that water inrush due to the destruction in intact floor is occurred along the "zero position destruction" line,the water inrush in floor fault is related closely to the nature of fault and the size of worked-out area. The mechanism of water inrush from the fault is revealed. It is indicate that the physical analog simulation technique has an important value in the study on the water inrush mechanism in floor.