The invention discloses a distributed optical fiber sensor based expressway protective fence damage positioning system and a method thereof, and belongs to the optical field. The distributed optical fiber sensor based expressway protective fence damage positioning system includes: expressway detection station modules, wherein each expressway detection station module includes a distributed Brillouin temperature strain analyzer and a channel expansion module; an expressway detection module including strain cables and protective fences; and an expressway communication module including a network unit, an expressway data center, and a service terminal. The strain cables are fixedly mounted on the protective fences in a S-shaped arrangement manner; top ends of the strain cables are connected toports of the channel expansion modules through end-to end optical fiber splices; ports of the channel expansion modules are connected to optical interfaces of the distributed Brillouin temperature strain analyzers through optical fiber patch cords; the distributed Brillouin temperature strain analyzers are connected to an expressway data center through the network unit; and the expressway data center is connected to the service terminal. The distributed optical fiber sensor based expressway protective fence damage positioning system effectively achieves the natural disaster early warning and special traffic safety accident alarm along the expressway.