Abstract: To address the issues of declining graded tailings concentration and escalating backfill costs in the Guizhou Jinfeng Gold Mine, comparative studies were conducted to evaluate the strength of backfill materials at varying slurry densities and cementitious additive proportions. Influential factors on the fluidity of the slurry and the strength of the backfill materials were analyzed. Additionally, the microstructure of the hydrated cementitious filler-graded tailings composite was examined using scanning electron microscopy. Under the premise that both strength and fluidity meet the design requirements, the cost of cementitious materials with different mix proportions was analyzed, and the backfill mix proportion with the best techno-economic efficiency was selected. The findings indicate that the use of cementitious filler as a cementitious material endows the backfill with enhanced early-stage strength, with its proportion having minimal impact on the slurry's fluidity. The primary determinant of fluidity is identified as the slurry density. Under identical density conditions, the uniaxial compressive strength of the backfill increases with an increment in the cementitious filler content. At a slurry density of 64 %, a cementitious filler content of 5.5 % yields a 7-day strength of 0.36 MPa, fulfilling the design specification of 0.35 MPa. When the slurry density is reduced to 62 % or 63 %, the cementitious filler content must be escalated to 6.5 %. At a slurry density of only 61 %, the cementitious filler content must be raised to 7.0 % to ensure compliance. The lowest backfill cost is achieved with a slurry prepared at a density of 64 % using a cementitious filler content of 5.5 %.