Abstract: This study focuses on the power supply system of Metro Line 8 in a certain city, proposing a 5G-enabled intelligent O&M real-time monitoring system for urban rail transit. Featuring a "two-level deployment, multi-level application" architecture, the system integrates edge computing, data fusion, AI recognition, and expert systems to achieve full-scope sensing, intelligent diagnostics, and closed-loop control of power equipment. Key aspects explored include system architecture, data acquisition, anomaly alerts, 5G communication coordination, and evolving maintenance strategies. Mathematical models and flowcharts illustrate the optimization logic. Results show that 5G significantly enhances system real-time performance, resilience, and predictive maintenance, offering strong technical support for smart metro O&M.