In order to reduce the ripple of the output voltage for the Superbuck converter, a control system based on small-signal modeling was proposed. Double closed-loop was used in control system, according to typical open-loop characteristic of the main topology for superbuck converter. Scheme, system diagram and the open-loop transfer function of the designed system was given in this paper. Simulation using Saber and Matlab was shown. The results show that the designed system has better output characteristic than the current designed systems.