Abstract: In order to solve the floor water inrush caused by serious roof pressure in deep mining under pressure of the Xingdong Mine, the risk and prevention technology of the water inrush from 2129 working face floor are studied by means of field investigation, theoretical calculation, stress monitoring and microseismic monitoring. The results show that the risk of the floor water inrush caused by serious roof weighting is still high under the complex mining geological conditions of the 2129 working face; It can effectively reduce the floor failure depth by shortening the periodic weighting interval; and the roof hydraulic fracturing to prevent the floor water inrush is proposed; during the mining process of 2129 working face, the average of the periodic weighting step is 5.25 m, which is 76% less than that of the 2222 working face; the maximum periodic weighting dynamic load coefficient is 1.47; and microseismic events are mainly concentrated in the shallow strata of the floor, while the floor water inrush channel isn’t formed. The proposed prevention technology can effectively reduce the risk of water inrush from the floor, realizing safe mining in the island working face under high water pressure.