Capacitor voltage imbalance is the key issue for the safe and reliable operation of cascaded H-bridge multi-level shunt active power filter (SAPF). This paper proposes a carrier exchange modulation technique based on DC capacitor voltage balance control by analyzing the impact of carrier phase shift modulation technique (CPS-SPWM) on DC side capacitor voltage, and establishes a combination of three closed-loop SAPF control strategy which includes a dual voltage loop and a current loop. This modulation algorithm is simple and easy to implement, and can achieve better compensation effect at lower switching frequency and effectively solve the DC side voltage balance problems for cascaded H-bridge multi-level SAPF at the same time. The simulation and experimental results show that the carrier exchange modulation technique is effective and practical, which could play a good control effect for DC capacitor voltage balance.