Abstract: Coal mining induces deformation and failure of floor strata, which make many disasters take place. Among them, it is most serious that confined water in Ordovician limestone below coal seams floods into tunnels or working faces. For slice mining of thick coal seams, because the rock stress in the first slicing is different from that in the second slicing and below, this may induce different characteristics of strata displacements in slice mining. In this paper, authors introduce the method of measuring floor strata displacements in slice mining, present the experimental data, and finally, give the displacement laws of floor strata for slice mining. The results are of great significance for preventing floor water irruption.