In order to cope with power quality problems and low utilization rate of regenerative braking energy(RBE) in double-modes traction system, a power transfer device integrating supercapacitor(PTDS) is proposed in this paper. A hierarchical control strategy containing an energy management layer and a converter control layer is presented, which can realize the rapid and accurate control performance. Based on the different operation states of the AC and DC traction systems, the energy management layer is divided into three working modes and ten working scenarios. The converter control layer realizes the reactive power compensation by controlling the AC-DC converter. Furthermore, by controlling the back-to-back converter in PTDS, the energy interconnection between the AC and the DC traction system is achieved. Moreover, the supercapacitor(SC), connecting at the DC bus, can store the RBE and release it to effectuate the peak clipping and valley filling. Finally, the feasibility of improving the power quality and utilizing the RBE of the proposed PTDS and its control strategy is verified.