Abstract: In response to the technical challenges faced by gold mines employing cyanidation gold extraction processes, such as the scarcity of backfill aggregates, the instability of traditional backfill performance, and high costs, this study conducted experimental research on lightweight energy-absorbing paste backfill. The basic physicochemical properties and energy absorption characteristics of the lightweight energy-absorbing backfill were systematically evaluated using XRD, slump and bleeding rate tests, uniaxial compressive strength tests, and triaxial compression mechanical behavior studies. The results indicate that when the dry density of the lightweight energy-absorbing backfill is between 500 kg/m³ and 650 kg/m³, the slurry bleeding rate ranges from 1.20 % to 1.45 %, achieving stable structural flow paste backfill. After 3 d of curing, the uniaxial compressive strength reaches 0.6–1.0 MPa. Furthermore, under triaxial confining pressure conditions, the material’s strength exhibits a positive correlation with increasing pressure, demonstrating excellent energy absorption characteristics. This research provides technical support for the subsequent promotion and application of lightweight energy-absorbing paste backfill in gold mines.