The invention discloses an MMC single-phase AC ground fault thermal shock inhibition control method based on an active bypass. A midpoint shifting control strategy and an active bypass control strategy are executed for an MMC, thereby effectively solving a problem that the thermal distribution of an MMC device is not uniform under the condition that a converter station is not locked, providing reactive and active support for a DC power grid, improving the reliability and stability of the MMC and the MMC device, and improving the AC fault ride-through capability. The midpoint shifting control strategy is used for solving a problem that the thermal distribution among three phases of the MMC is not uniform, and generating a newly added redundancy submodule at each phase. The active bypass control strategy employs the newly added redundancy submodules for bypass alternating, thereby effectively solving a problem that different submodules in the same bridge arm are not uniform in thermal distribution. Meanwhile, a bidirectional transistor bypass submodule which is strong in overcurrent capability, protecting a lower transistor IGBT of the MMC submodule and a reversely parallel diode from being damaged by the long-time passing of a larger current.