Abstract: The rapid charging and discharging characteristics of supercapacitor can meet the need of metro vehicle frequent starting and stopping. Based on the principle of constant voltage bi-directional power flow, a model of metro vehicle on-board supercapacitor energy storage system is established. On the basis of satisfying the recovery of metro vehicle braking energy, the configuration of supercapacitor banks is optimized. The full life cycle cost calculation model, supercapacitor life calculation model and economic benefit calculation model of the on-board supercapacitor energy storage system are established. Through practical calculation case, the supercapacitor in the on-board system is configured, its economy is evaluated. The result shows that the system can achieve the expected economic benefit.