With the widespread application of information technology in the instrumentation and control (I&C) systems of nuclear power plants, cybersecurity and functional safety have become key factors for ensuring the safe and stable operation of nuclear power plants. This paper systematically reviews domestic and international regulations and standards related to cybersecurity and functional safety, and explores the relationship between them. Through case studies, it illustrates the implementation scheme of safety-class distributed control systems (DCS) considering the interactions between cybersecurity and functional safety. The research provides guidance for the subsequent implementation of safety-class I&C system schemes.