The bidirectional dc-dc converter plays a vital role for interfacing the energy storage units to the internal dc-bus in the power conditioning system. Compared to the commonly used four-switch buck-boost (FSBB) converter, the six-switch buck-boost (SSBB) converter offers the advantages of higher input voltage rating, wider input voltage range, and enhanced control flexibility. This paper investigates the modulation and control for the SSBB. The soft-switching modulation scheme is proposed for achieving zero-voltage-switching for all power switches, and the multiple mode control is proposed for minimizing the inductor current ripple throughout the entire input voltage and output load range. Finally, simulation results are presented to verify the effectiveness of the proposed control scheme.