Abstract: In the traditional three-layer capacitor voltage balance control of the three-phase cascaded H-bridge STATCOM, the dynamic performance of the clustered voltage balance control is poor, and it causes harmonics to the power grid. This paper proposes a clustered voltage balance strategy based on model predictive control, which can suppress DC voltage fluctuation at the same time. The proposed control strategy introduces a new cost function, which has the characteristics of balancing clustered voltage and suppressing DC side fluctuation. Based on this cost function, the injected zero-sequence voltage can be flexibly controlled to improve the dynamic performance of clustered voltage balance within the remaining modulated voltage range. Meanwhile, the fluctuation of capacitor voltage on the DC side voltage is also suppressed. The proposed control method makes use of the residual modulation voltage of the system, so that the system can avoid the problem of over-modulation without limiting the amplitude of the injected zero-sequence voltage, which simplifies the control system. Experimental verification was carried out on the five-level star-type cascaded H-bridge STATCOM experimental platform. The experimental results show that the clustered voltage equalization scheme based on model predictive control can effectively improve the dynamic performance of clustered voltage balance and suppressing DC side voltage fluctuation.