To ensure the safe, reliable, and stable operation of nuclear power plants, the instrumentation and control (I&C) systems of nuclear power plants provide various control, protection, and monitoring methods for the plants processes and equipment. This paper conducts extensive research on literature and data related to the development of domestic nuclear power I&C systems. By examining the current usage of I&C systems in operational and under-construction nuclear power plants in China, it outlines the evolutionary process—from the initial analog instrumentation with relay-based control, to analog control combined with non-safety digital monitoring, and finally to the gradual adoption of fully digital I&C systems, including safety-class systems. Additionally, this paper analyzes the characteristics of modern digital I&C systems and summarizes the design principles for nuclear power instrumentation and control. Finally, it explores and forecasts future technological advancements in nuclear power I&C systems. By clearly outlining the current applications and providing a detailed analysis of development trends, this paper offers valuable insights for the future growth of the nuclear power I&C industry.