Abstract: In the modular multilevel DC/DC converter, the traditional phase-shifted carrier pulse width modulation（PWM） leads to the larger inductor current ripple when the modules have different input and output voltages. As a result, the inductor loss increases and the optimal design of filter devices are difficult as well. Aiming at this problem, through the frequency-domain analysis of current ripple, this paper reveals the problems of traditional phase-shifted modulation technique. In addition, the relationship among the current ripple, input and output voltages of modules and carrier phase-shifting angles are analyzed. The carrier phase-shifting angle of each module is calculated with the goal of minimizing the switching frequency harmonic amplitude in the current ripple. The calculation method of the phase-shifting angle is adjusted according to different conditions, and a modulation strategy for current ripple suppression is realized. Finally, the software simulation and experimental test of the modular multilevel DC/DC converter with three cascaded modules are carried out. Both simulation and experimental results show that the proposed control strategy can effectively reduce the current ripple when the input and output voltages of each module are unequal, which verifies the correctness and practicability of the proposed control strategy.