Based on passive optical devices, the highly redundant fiber Bragg grating (FBG) sensor module was proposed and designed. Then the FBG sensor network with high redundancy based on the FBG sensor module and wavelength division multiplexing technology was built. Using rectangular aluminum alloy plate with highly redundant FBG sensor module array as the research object, the reliability of the highly redundant FBG sensor network was analyzed, and the applicability and reliability of the FBG sensor array with high redundancy were verified by theory and experiments. Research results show that the redundancy of FBG sensor network can be improved by switching optical switch between the different branches of sensor array. It not only solves the problem that some FBG sensing signals lost caused by several failures in the FBG sensor network, improving the reliability and fault tolerance of FBG sensor network, but also provides an effective and feasible monitoring method for structural health monitoring and special site monitoring in engineering applications.