A high-flux silicon carbide ceramic filter membrane and a preparation method thereof are provided. In the preparation method, a separation layer is directly coated at a time on the basis of a support, that is, after the support is sintered, the separation layer is directly coated and then sintered for carbon removal. In the present disclosure, a sintering process and a coating formula are optimized to prevent fine silicon carbide particles from entering micropores of a support due to capillary filtration and film formation during coating, such that a separation layer with an average pore size of 0.2 μm or less can be directly coated on a silicon carbide support with an average pore size of 10 μm or more, and fine silicon carbide particles can be effectively prevented from entering micropores of the support during the coating.