The invention relates to a preparation method of silicon nitride and silicon carbide combined tantalum boride foamed ceramic. The method is characterized by comprising the steps of evenly mixing TaB2, silica powder, phenolic resin and a hydroxypropyl methyl cellulose solution to prepare ceramic slurry; then, dipping the ceramic slurry onto polyurethane foam, drying and then firing the silicon nitride and silicon carbide combined tantalum boride foamed ceramic in the nitrogen atmosphere. The silicon nitride and silicon carbide combined tantalum boride foamed ceramic is uniform in microscopic structure, high in strength and even in hole size, and is capable of avoiding the residue of carbon and free silicon; the strength, the high temperature resistance and the thermal shock resistance are greatly improved.