Solid backfill mining has been applied to excavate coal seams under aquifers in China; however, the control effects of the water-conducting fractured zone (WCFZ) require further study. Therefore, based on the mechanical properties of the compacted backfill materials, a method for simulating these materials has been proposed, and the compaction of backfill materials subject to the effects of overlying strata has been simulated. Boreholes were used in the test area to measure the height of the WCFZ in the CT101 panel of the Wugou Coal Mine in Suixi Town, Anhui Province. The results indicate that the numerical simulation is basically consistent with measured data, which verifies the feasibility of the simulation method. Moreover, the backfill materials were placed into the gob to restrict the movement of rock strata, which helps reduce the mining impact and the height of the WCFZ. The research results provide a basis for the design of backfill mining under aquifers.