Based on the compressive experiment of statics properties of air-dried and water-saturated sandstone from Kaiyang Phosphate Mine,the statics mechanism of rock-burst prevention with water is discussed.The static load experiment of water-saturated sandstone showed that water can decrease its static strength and its capability of accumulating elastic energy and can increase its deformation.With surrounding rock of three-centered arch roadway softened by water,its peak value of abutment pressure reduces obviously and transfers to deep place,so all of these can effectively decrease the probability and level of rockburst occurrence.