With the rapid application of master-slave network systems, which become more and more extensive. The structure of the system become more and more complex, so the security and reliability of the system has become the basic requirement of system design. Therefore, this paper designs the redundant architecture and switching method for the master-slave network control system. In the case of equipment working error or the communication failure, the system chooses relatively stable equipment and communication network through automatic fault switching strategy to realize system fault self-recovery. Based on Markov process theory, the system working state switching model is established. By comparing the reliability of the system with or without redundancy function, it is verified that the redundant design of the master-slave network control system can greatly improve the reliability of the system.