Horizontal vacuum filter is a device that uses vacuum negative pressure as a driving force to achieve solid-liquid separation. Under the action of vacuum negative pressure (0.04-0.07MPa), the liquid in the suspension is extracted through the filter medium (filter cloth), while the solid particles are intercepted by the medium, thus achieving the separation of liquid and solid. The filtering section is arranged along the horizontal length direction in the structure, which can continuously complete tasks such as filtering, washing, drying, and filter cloth regeneration. The rubber belt filter has the advantages of high filtration efficiency, large production capacity, good washing effect, low moisture content in the filter cake, flexible operation, and low maintenance costs. Rubber belt filter can be widely used for solid-liquid separation in metallurgy, mining, chemical industry, papermaking, food, pharmaceuticals, environmental protection and other fields, especially in gypsum dehydration (FGD) in flue gas desulfurization.