IEC62439-3 describes parallel redundancy protocol (PRP) and high availability seamless redundancy (HSR) in detail. However, these redundancy protocols are transparent to upper layer, supervision system cannot identify the single link failure. In order to resolve this problem and achieve good maintenance experience of PRP and HSR redundant network, the implementation process of PRP and HSR redundancy is analyzed, the action principle of detecting frame is researched, and a redundancy network supervision system based on detecting frame is built. The specific redundancy detecting principle and implementation method are put forward, and the advantages of this system are summarized and analyzed, which provides an effective solution for the redundancy network supervision of smart substation.