The wide-range input voltage for unidirectional DC/DC converter in fuel cell system will caused by soft output characteristic of fuel cell, which limits the applications of the DC/DC converters. According to the dual switch Buck-Boost cascaded circuit can automatically change the Buck or Boost working mode according to the input voltage to acquire proper constant or adjustable output voltage, the dual voltage/current close-loop control circuit based on the average current control has been designed for this circuit in this paper, in order to realize the dual switch Buck-Boost cascaded circuit acquire constant output voltage during wide-range input voltage, which can provide stable input voltage for later stage converter in fuel cell system to decreases the difficulties in design, optimization of later stage converter, and effectively solve the high voltage stress in conventional single switch Buck-Boost circuit. Simulation results and experiment research with low power prototype verify the excellent performance of dual switch Buck-Boost cascaded circuit with the proposed dual close-loop control circuit during wide-range input voltage.