Given the fact that urban rail train impacts the traction network voltage during the starting and brak- ing and brings about the negative impact of the grid voltage instability, this paper proposes a hybrid energy stor- age system composed of a super capacitor and a lithium titanate battery, which meets the demand of urban rail trains for high energy and high power. Taking the overall structure of the hybrid energy storage system as the re- search object, the design and simulation verification of the precharging circuit were introduced, which may sig- nificantly improve the performance of the hybrid energy storage device and prolong the service life. Based on the structure, an integrated control strategy was proposed, which realized the operation of the energy storage unit in the constant current charge and discharge state by controlling the working modes of the two bidirectional DC/DC converters in the main circuit. Finally, the simulation compared the proposed control strategy with the traditional voltage-current double closed-loop control strategy. The simulation waveform comparison analysis shows that the control strategy proposed in this paper can be more effective for the fluctuation of the network voltage caused by the sudden increase and decrease of large-capacity load such as traction locomotive. The rapid adjustment of the charging and discharging state of the hybrid energy storage system ensures that the fluctuation of the traction network pressure is small, and the operational reliability and stability of the urban rail train are improved.