Capacitor voltage control and circulation current suppression are of great importance in the research of MMC topology. In the meantime, they are also the bottleneck restricting the application of MMC topology in the field of flexible high voltage direct current (HVDC). This paper analyzes generation mechanism of the capacitor voltage fluctuations and even harmonics circulation current in MMC. Based on the strategy of carrier phase-shift modulation (CPS-SPWM) by sorting and equalizing voltage, the capacitor voltage balance control is added so as to suppress the capacitor voltage fluctuation. In addition, the paper introduces a close-loop resonant circulation controller to realize suppression of AC component of the circulation current. This control method has simple structure and is suitable for single-phase system. Simulation results show that both the capacitor voltage fluctuation and circulation current can be well suppressed with the proposed method. The dynamic results are also good.