Abstract: Objective: The relay protection device in metro power supply system suffers from drawbacks such as heavy reliance of group network on switches, distinct relay protection device information boundaries between AC and DC sides of the power supply system, and poor information exchange capability among relay protection devices at different stations along the line. To address these issues, a crossstation networking protection scheme for metro power supply system based on HSR (highavailability seamless redundancy) as specified in the IEC 624393:2010 standard is proposed.Method: The current status of relay protection device in metro power supply system is introduced, together with the structure and working principles of HSR. The networking scheme, key technologies, and equipment involved in the crossstation networking protection scheme based on HSR for metro power supply system are presented. A laboratory test platform is set up to simulate the data flow of protection devices between three adjacent substations along the same metro line, in order to verify the network reliability and realtime transmission of the HSR group network scheme.Result & Conclusion: HSR can avoid network switching time and data loss risks, and the group network reliability achieved by HSR is comparable to that of a dualstar network. Under both bilateral power supply mode and large bilateral power supply mode, the relay protection devices operate normally, meeting the requirements of network realtime transmission and reliability. The proposed protection scheme reduces the complexity of onsite wiring, lowers upfront engineering costs and subsequent maintenance expenses, showing significant economic benefits.