Abstract: To study the mechanical and flow properties of coal-based solid waste backfill under the influence of multiple factors, an orthogonal experimental design was used to analyze the influence of bone-cement ratios, mass concentration, fine aggregate content, and fiber content on the performance of the backfill. A prediction model for the strength and flowability of the backfill was constructed, and the mechanism of the influence of changes in influencing factors on the mechanical properties of the backfill was revealed. Based on the fuzzy mathematical comprehensive evaluation model, the ratio parameters of the coal-based solid waste cemented backfill were optimized. The results showed that the flowability of the slurry decreased with the increase of mass concentration, fine aggregate content, and fiber content, and the increase of bone-cement ratios slightly increased the flowability of the slurry. The compressive strength of the backfill significantly decreased with the increase of bone-cement ratios, while the increase of mass concentration and fine aggregate content could effectively improve the compressive strength of the cemented backfill. Adding an appropriate amount of fibers could enhance the strength of the backfill, and the optimal dosage range was about 0.2%. The increase in mass concentration, fine aggregate content, and fiber content could weaken the weakening effect of the increase in cement-bone ratios on the compressive strength of the backfill. The increase of bone-cement ratios would deteriorate the compactness of the microstructure of the filling material, thereby deteriorating the compressive strength of the backfill. Adding an appropriate amount of fine aggregate particles could reduce the scale and range of the internal void structure of the backfill, improve the density of the microstructure of the backfill, and thereby enhance the mechanical properties of the backfill. The optimal proportioning parameters for the filling material based on the fuzzy mathematical comprehensive evaluation model were as follow: bone-cement ratios of 8, mass concentration of 80%, fine aggregate content of 70%, and fiber content of 0.4%.