Abstract: To solve such defects as low control accuracy and narrow output voltage range of high-capacity charging device for supercapacitor caused by voltage fluctuation, a supercapacitor based DC/DC converter with wide input range was researched. Utilizing two-stage conversion of buck-phase shift full bridge (Buck-PSFB) the converter possessed both features of wide voltage regulation range and soft-switch of load phase-shifting full-bridge converter at same time. By means of analyzing the equivalent circuit model of supercapacitor, a power loop based voltage-current double loop control method to control DC bus voltage and current, which could follow the variation of input voltage variation rapidly and hold the bus current steady, was proposed. In view of the above, a simulation model was constructed on Matlab/Simulink platform for the analysis. Finally, the feasibility of the proposed control method is verified by applying it to 300kW bus charging pile of public traffic system in Minsk, Belarus.