A new fault location method for the smart grid based on High-availability Seamless Redundancy (HSR) protocol is designed. The transmission mechanism of an HSR_Supervision frame is used and the padding field is optimized. When each node in the HSR network receives the HSR_Supervision frames sent by other nodes, a table named AllNodeConnectTable of this node is formed to reflect the whole network topology. In the process of operation, when a fault occurs on a communication fiber or a node on the HSR ring, other nodes fail to receive the relevant supervision frames. The AllNodeConnectTables are changed, from which the fault location in the corresponding ring is determined accurately. This paper introduces in detail the design principle of fault location based on the HSR_Supervision frame and the location method of typical faults. This work is supported by Science and Technology Project of State Grid Corporation of China (No. 520940180036) “Secondary System Architecture and Key Equipment Research for the Third Generation Intelligent Substation”.