Abstract: The paper firstly analyzed several problems in the current O & M (operation and maintenance) of the process-level network of smart substations, and gives corresponding solution technology or scheme for each problem. Then, corresponding technologies such as port mirroring, switch model optimization, port whitelist filtering, switch automatic configuration, port monitoring statistics, and networking scheme optimization, etc are illustrated and analyzed. Based on the experimental environment, a simulation test system was built to simulate the mirroring function, whitelist function, and flow control function of the switch. Simultaneously, the fiber link monitoring function was simulated and verified. The verification results show that the process-level network fault location of the solution is accurate, fiber link warning is in time. The above technologies can improve the O & M level of the process-level network of the smart substation, and even reduce the cost of networking. Combining the above technologies can form a complete process-level network O & M plan and can accurately locate faults, improving the overall O & M management capabilities of smart substations.