The invention discloses a gradient pore silicon carbide ceramic filter plate and a preparation method thereof, and belongs to the field of filtering media. Coarse pore, medium pore and fine pore soft polyurethane foam bodies are cut into the same size of wafer shapes, the wafer shapes are in turn soaked with a sodium hydroxide solution and a sodium carboxymethyl cellulose solution to obtain coarse pore, medium pore and fine pore pretreated soft polyurethane foam bodies, silicon carbide, kaolin and the like are mixed by ball milling, all size levels of composite powder are screened, and respectively evenly mixed with deionized water and aluminium dihydrogen phosphate to obtain all size levels of ceramic slurry, the all size levels of ceramic slurry are added into respectively the coarse pore, medium pore and fine pore pretreated soft polyurethane foam bodies for soaking, rolling and stacking neatly according to the order of coarse pores, medium pores and fine pores to obtain a combined foam body, the combined foam body is dried, and the gradient pore silicon carbide ceramic filter plate is prepared by hanging slurry and drying of the combined foam body. The beneficial effects are that the gradient pore silicon carbide ceramic filter plate has high strength, ceramsite is not easy to flake off, the opening porosity is high, and the pores are not easy to be plugged.