Abstract: Tailings thickening is an important process of paste filling technology. At present, a deep cone thickener is often used for tailings thickening. The sedimentation rate of tailings affects the solid flux of the deep cone thickener and determines the area occupied by the deep cone thickener. At present, the addition of flocculant to tailings has become a common practice to improve the efficiency of tailings thickening. Thus, the influence of various factors on the solid flux of the deep cone thickener needs to be investigated. In this study, the solid flux of the deep cone thickener was calculated through the static sedimentation experiment of the graduated cylinder, and the influence law of the flocculant unit consumption and slurry concentration on the solid flux of the deep cone thickener was analyzed, and the influence of the two factors on the solid flux of the deep cone thickener was determined. Results showed that the tailings exhibit a quadratic function relationship when the flocculant unit consumption is 5–30 g·t⁻¹. At 6%–26% solid mass fraction of slurry, the solid flux first increases and then decreases, which is consistent with the experiment. The regression analysis of the solid flux equation under the coupling effect of flocculant unit consumption and slurry concentration shows that the contribution of the two factors to solid flux is slurry concentration > flocculant unit consumption. Based on the analysis of the influence of flocculant unit consumption and slurry concentration on solid flux, the reasons for the different contribution values of flocculant unit consumption and slurry concentration were summarized. According to the mathematical relationship between flocculant unit consumption, slurry concentration, and solid flux obtained from the research, engineering suggestions for the design and operation of the deep cone thickener were proposed. During the operation of the deep cone thickener, the slurry concentration should be guaranteed first, followed by the flocculant unit consumption.