Abstract: Cemented backfilling is an effective method for controlling the roof stability of goaf. To quantitatively evaluate the load-bearing control effect of backfilling material on the goaf roof, biaxial compression tests were conducted under lateral confinement condition. The mechanical properties and strength-aging characteristics of the backfilling material at different curing ages were analyzed. Field measurements were carried out to determine the roof deformation and stress evolution patterns of the backfilling material under cemented backfilling condition. A novel index for evaluating the filling effectiveness in goaf was proposed and validated through numerical simulation. The results indicate that the compressive strength of the backfilling material exhibits an exponential increase with curing age, reaching approximately 4.6 MPa at 2 days and its maximum value (about 7 MPa) at 7 days. Field data show that the maximum compression of the backfilling material in the goaf is 80.9 mm (accounting for 4.3% of the mining height in the working face), the stabilized stress value of the backfilling material is 2.37 MPa, achieving stability after advancing 90 m, with distinct staged evolution characteristics. At a mining rate of 4.0 m/d, the safety factor of the backfilling material is 1.38, and the compaction coefficient approaches 1. Numerical simulation results reveal that cemented backfilling reduces the height of the plastic zone in the roof by 78.4% compared to caving mining, decreases the maximum vertical displacement at the center of the goaf by 83.6%, and lowers the peak vertical stress in the overburden by 36.4%. These findings demonstrate the significant effectiveness of cemented backfilling in controlling stability of goaf roof.