Modular Multi-level Converter (MMC) Flexible DC transmission is considered to be the most competitive HVDC mode. MMC circulation suppression strategy based on the PR controller has been widely used and can effectively reduce the circulation component of bridge arm. However, when the grid voltage is not symmetrical, the zero-sequence current component in the bridge arm current will enter the DC side to cause the DC voltage / current 2 times frequency fluctuation, and the existing control strategy can not suppress it well. And the existing loop control model can not fully reveal the inherent characteristics of MMC, which also hinders the further understanding and application of MMC. Aiming at the above two problems, an accurate circulation control model is proposed, which points out the relationship between the internal circulation electrical quantity of MMC. On this basis, a new circulation suppression strategy is designed, and a ± 100 kV/300 MW MMC-HVDC simulation model is built in Matlab. Simulation results show that the proposed control strategy can both reduce the bridge arm current and DC voltage ripple, and improve the MMC-HVDC fault ride through capability. This work is supported by National 02 Special Foundation of China—Power Grid Equipment Development and Test Platform Construction based on Domestic IGBT (No. 2015ZX02301003).