The flowability and mechanical properties are increasingly crucial in the filling process of deep metal mines with mining depths exceeding 1000 m. The rheological properties of filling slurry in the pipeline were analyzed through rheological tests, L-tube self-flow tests, and semi-industrial loop tests. The results revealed that with an increase in the cement-to-tailings mass ratio (c/t ratio) and mass concentration, the slurry exhibited a higher flow resistance and decreased stowing gradient. During slurry transportation, the pressure loss in the straight pipe was positively correlated with the slurry flow rate, c/t ratio, and mass concentration. A uniaxial compressive strength (UCS) test was conducted to analyze the mechanical properties of the cemented paste backfill containing BMC (CCPB) in both standard and deep-underground curing environments. The UCS of the CCPB showed an increasing trend with the rise in curing age, mass concentration, and the c/t ratio. The comprehensive analysis concluded that when the c/t ratio is 1:4, and the mass concentration is approximately 74%, and parameters such as the slump, bleeding rate, and flowability of the filling slurry meet the criteria for conveying and goaf filling, resulting in a high-strength filling body.