When a grounding short circuit occurs on the DC side of a modular multi-level converter (MMC), the fault current has the characteristics of fast rise and high peak value. To reduce the breaking stress of the circuit breaker, the dynamic process of the sub-module and the bridge arm is analyzed from the point of view of energy. An equivalent discharge model of an MMC under DC fault considering the influence of AC power is established, and the expression of fault current is derived. An active current limiting strategy based on AC side feeding is proposed. By introducing feed-forward control, the control block diagram with physical current limiting resistance is transformed, and the DC side current limiting resistance is increased equally, and its parameters are adjusted. Then part of the energy of the capacitor during the fault is fed to the AC side, so as to reduce the current rise rate and peak current during the fault. This control method not only suppresses the discharge from the AC side power supply to the fault point, but also reduces the discharge current from the DC capacitor to the fault point. Finally, a four-terminal ring MMC transmission network model is established in PSCAD/EMTDC to verify the feasibility of the proposed scheme.