The invention discloses a high-performance oxygen-evolution CoSn2/Ni3Sn4@NC/C composite catalyst and a preparation method and application thereof. The composite catalyst is prepared in the step that cobalt-nickel selenide nano-particles and nitrogen-doped carbon are supported on a carbon material together. The preparation method comprises the steps that after a nitrogen-containing small organic molecule compound, cobalt salt and nickel salt are subjected to liquid mixing, a solvent is evaporated, drying is conducted, the mixture of the nitrogen-containing small organic molecule compound, the cobalt salt and the nickel salt is subjected to first calcination in a protective atmosphere, a calcined product and a carbon material are uniformly stirred in a dimethylformamide-water mixed solutionand then subjected to a solvothermal reaction, and a product obtained after the solvothermal reaction is subjected to second calcination in a protective atmosphere to obtain the high-performance oxygen-evolution CoSn2/Ni3Sn4@NC/C composite catalyst. The preparation technology is simple, low in cost and beneficial for industrial production; when used in a storage and conversion system of renewableenergy sources, such as water splitting or metal-air secondary batteries, the composite catalyst prepared by using the method has the advantages of being high in activity and high in stability; compared with a commercial RuO2 catalyst, the high-performance oxygen-evolution CoSn2/Ni3Sn4@NC/C composite catalyst is higher in combination property and shows a good application prospect.