Structural material steel is the main material used for valves of nuclear power plant. Relevant regulations do not allow the use of cast iron valves on equipment (reactor, steam generator, vessel and pump shell, etc.) and pipelines of nuclear power plant. Cast iron materials are only used for minor, light load driving mechanism parts and the manufacture of non critical valves in auxiliary systems. Bronze can be used on stem nut, shaft sleeve and drive shaft sleeve of valve. For those places where regulations do not need to be implemented (pipelines and equipment with low pressure, cold medium and small nominal size on the auxiliary system, etc.), in addition to steel valves, valves of other materials can also be installed. It is very important and necessary for all links on the process cycle circuit of nuclear power plant to work without accidents, which urges people to treat its economic problems carefully, Although it would be more economical to use cheaper materials than steel, it is not as good as steel in strength and wear resistance. The structural materials shall ensure the lasting strength of the valve parts under the temperature of the working medium, and shall have wear resistance, corrosion resistance, thermal stability and heat resistance under the given medium. According to the working conditions and functions of the valve, a set of requirements for the main materials of the parts are put forward. Temperature is one of the most important factors that determine the working conditions of valves and the selection of parts and materials. Generally speaking, the valve body material of the valve shall be the same as the pipe material connected to it. Therefore, the basic requirements for valve body material and pipe material are also the same. However, there may be exceptions, such as valves on auxiliary piping.