Objectives: To verify the energy efficiency operation of electrified trains on the certain metro line, in Vietnam by combining two solutions to recover regenerative braking energy with on-board supercapacitors and tracking the optimal speed profile. Methods: This study proposes an integrated optimization method: applying Pontryagin's maximum principle (PMP) finds the optimal speed profile with fixed running time and recuperating regenerative braking energy by designing the control method -Current Mode Control (CMC) to manage charge/discharge process of the on-board supercapacitor energy storage system (SCESS) tracking the optimal speed profile. Findings: With this approach, a considerable reduction in consuming energy obtained for Cat Linh-Ha Dong metro line, Vietnam has been verified by simulation results on MATLAB and MAPLE software indicating that applying PMP, the highest operation energy saving is 10.15%, but if both solutions PMP and SCESS are applied, the energy saving level increases up to 14.7% in comparison with simulation results of the case of original speed profile. Novelty: Combining two energy saving solutions simultaneously: applying PMP to determine the optimal speed profile and using super-capacitors with CMC algorithm have recuperated the regenerative braking energy. The level of energy saving is higher than other saving solutions.