Abstract: A redundant design of control station in digital safety I&C system for nuclear power plant was introduced. A hot-backup redundant system was built by two asynchronous main controllers, which composed identical hardware. The two redundant controllers used CPLD (complex programmable logic device) to exchange status and execute arbitration. A specified link made by FIFO (first in first out) device and Ethernet PHY (physical layer) device implemented the data synchronization between the two asynchronous controllers. This design was put into practice in the design of digital I&C safety system, reached a short master-slave switching time with no disturbance, and improved the system’s reliability.