The aims to study the corrosion mechanism and prevention and control technology of high-voltage DC converter valve radiator. By constructing a radiator water-cooling system operation platform, two different water-cooled radiators, electroless nickel plating and non-nickel plating, were used to study the corrosion and influence of the water-cooled inner flow passage. The corrosion condition and the composition of the corrosion products were analyzed by SEM and elemental analyzer, and the mechanical properties of the metal materials were studied by a universal testing machine to derive the corrosion mechanism. The change law of heat exchange efficiency between nickel-plated and unnicked water coolers is also compared. A test platform capable of evaluating the corrosion performance of the water-cooled radiator was successfully built. Under the simulation of the test platform, the nickel-plated water-cooled radiator was bright after 3 months of running on the water-cooled equipment, and there was no obvious corrosion and corrosion marks; Nickel water-cooled heat sinks have obvious corrosion products on the macroscopic and microscopic scales, mainly composed of hydroxyaluminum, aluminum sulfate and aluminum chloride. Moreover, the electroless nickel plating cathodic protection treatment can reduce the thermal conductivity of the fluid during convective heat transfer, and the flow of the fluid in the flow channel becomes a violent disordered turbulent state. The electroless nickel plating cooling system has better corrosion resistance and can reduce the thermal resistance of the water-cooled radiator, thus enhancing the heat exchange effect and improving the heat transfer performance of the water-cooled radiator. It provides a direction for HVDC project application, radiator corrosion and heat transfer efficiency.