Abstract: At present, the nuclear grade pressure reducing valve of AP1000 used in the ventilation system of the main control room is imported. In order to break the foreign technical monopoly and form its own intellectual property, the domestic R＆D on the valve for CAP1400 has been carried out. This paper puts forward the R＆D technical requirements, introduces the structural characteristics, and expounds the key points and focus from the aspects of structural design, material selection, sealing performance,processing technology, nondestructive inspection and identification test. The identification test results show that the structural design of the valve fully meets the technical performance requirements, the localization R＆D is realized, which provides a good reference for the subsequent design.