The nuclear safety-class DCS realizes important functions such as reactor protection and actuation of dedicated safety systems in nuclear power plants. It involves a large number of devices with high safety levels and diverse types. In addition to the main controller modules and input/output modules, engineering materials are also an important part of the nuclear safety-class DCS, realizing key functions such as power distribution and signal transmission. To meet the requirements of high reliability and maintainability of the nuclear safety-class DCS, engineering materials should be selected with appropriate models and consistent among devices. Summarizing the selection principles and methods of commonly used engineering materials and forming a standardized selection system can help improve design efficiency and quality. Combined with practical cases, the effectiveness and guiding value of this selection method have been verified.