Abstract: In order to explore whether mining the No.16_up coal seam of lower-group coal in 10603 working face in No.10 mining area of Yangcun Coal Mine makes the activation of the 10605F5 reverse fault and causes gushing water from the floor, a mechanical model of floor fault activation considering water pressure and a numerical model of fluid-solid coupling including fault mining were established. The paper analyzes whether the fault will be activated, the variation characteristics of plastic zone of roof and floor and fault during the mining process, and the pore water pressure variation characteristics at different positions of the fault zone under the coupling effect of mining stress and confined aquifer water pressure. The research shows that under the coupling action of the mining stress and the water pressure of the floor aquifer, the confined water of the floor will guide up a certain height along the fault zone, and most of fault area below the working face still have good impermeability. Therefore, the water of the floor aquifer will not inflow to the working face along the fault, and mining in the working face will not lead to fault activation. This study results can provide good guidance and reference for the water control of lower-group coal of fault mining floor in Yangcun Coal Mine.