Abstract: Water in-rush of coal floor is a complex geological and mining-affected phenomenon，which refers to the natural disaster that the confined water under the coal seam breaks through the blockage of the floor isolation and comes into the mined-out area of working face in a rush，relax or delayed manner，leading to the increase of water inflow or even submerge the mine.Therefore，it is very necessary to study the forecast method of floor water in-rush and its prevention and control measures.In light of the occurrence characteristics of No.6 coal seam in Zhuzhuang Coal Mine of Huaibei Mining Group，and based on large amount of site measurement and theoretical analysis，the forecast method of water in-rush of floor in mining over confined water body and its prevention and control measures were proposed，and the water prevention and control plan was determined，ensuring the safe mining of No.6 coal seam over confined water body.

Key words: Floor water in-rush, Forecast method, Prevention and control measure, Consolidation by grouting