Abstract: To improve the utilization of regenerative braking energy in metro train operation, an optimized control method based on a flywheel energy storage system is proposed. First, a mathematical model of the regenerative braking energy was established, and the energy feedback process during train operation was systematically analyzed. Then, the structural model of the flywheel energy storage system was constructed, with its energy conversion mechanism between electrical and mechanical forms examined. To address the dynamic characteristics of the storage motor, performance comparisons were carried out among PI control, fuzzy PID control, and particle swarm optimization-based fuzzy PID(PSO-Fuzzy PID) control. The results show that the proposed system can recover approximately 862 224 kWh of energy annually for a single train. Compared with conventional PI and fuzzy PID controls, the PSO-Fuzzy PID strategy demonstrates superior performance in terms of response speed, overshoot, and steady-state accuracy, along with enhanced anti-interference capability and dynamic stability. Experimental results validate the effectiveness of the proposed control strategy for the metro regenerative braking energy storage system, providing important technical support and a theoretical basis for energy-saving and green rail transit operations.