The invention discloses a method for switching an industrial redundancy server, comprising the following steps: a, a CPU (Central Processing Unit) is respectively in telecom connection with a first server and a second server; b, the CPU reads fault states of the first server and the second server regularly; and c, according to read fault state values in the step b, the CPU performs master-slave determination on the first server and the second server. The method is used for expanding a communication process of a traditional control system. The master slave relation of the redundancy server is determined by using the CPU. Because two servers existing in the switching process of the redundancy server are master servers or slave servers, the master-slave determination problem in the switching process of the redundancy server can be resolved.