Abstract: Based on the features of the deep depth seam, high water pressure, thin water isolated layer in floor and others in Zhaogu No.1 Mine, in order to maxim ally recover the coal resources and to realize a safety and high efficient production, the DC electric method site measurement, the similar simulation experiment, the fini te difference numerical calculations, the discrete element numerical method and other means were applied to predict the floor failure depth in No. 11011 coal mining fac e in No.Two1 seam of Zhaogu No.1 Mine.With the analysis on the floor water isolation and evaluation on the water inrush, a completed set technology system suitable t o study the floor water prevention and control for the coal mining face was established.The analysis showed that the water inrush danger of No.8 limestone under the fl oor of the No.11011 coal mining face would be high and the water inrush possibility of the No.2 limestone, No.3 limestone and Ordovician limestone under the floor woul d be small.