Because of the module's negative-level output performance of the full bridge, the hybrid MMC with an AC modulation ratio greater than 1 is satisfied. The optimal design of hybrid MMC ratio based on high AC modulation ratio, which can reduce the DC failure and increase the AC grid voltage level. The operating area of DC voltage is extended. It is of great significance to the development of flexible HVDC transmission. Therefore, a full-bridge proportional constraint considering DC fault ride-through and half-bridge sub-module capacitor-voltage balance based on the high AC modulation ratio was proposed. The transient characteristics of DC faults and the voltage fluctuations of half-bridge sub-module capacitors were analyzed in ±500kV double-ended hybrid MMC system model. The comprehensive optimization design scheme of the mixed MMC ratio was obtained. The results show that the propor-tion of the full bridge should not be less than 41%. The system voltage recovery time is first reduced and then increased after the fault. The fault self-clearing time is shortened, and the half-bridge sub-module capacitor voltage fluctuation is reduced by 8.15kV. The capacitor voltage fluctuation is positively correlated with the AC modulation ratio. The module fault handling capability and overall performance of MMC with a full bridge ratio of 75% is better. The research results provide a reference for the lightweight design of MMC.