To improve the uninterrupted operation capability of hybrid modular multilevel converter (MMC), the control strategy considering unbalanced grid fault is proposed in this paper. A control loop including ANF-PLL, quasi resonant part, low voltage current limiting and zero-sequence circulating current suppressing is added based on AC/DC decoupling control. The negative-sequence current is suppressed, the overcurrent of the arm is limited and the zero-sequence double frequency current is eliminated. Firstly, the converter model under unbalanced condition is introduced. The impact is analyzed based on the expression of power and arm current. Then the negative-sequence current suppression strategy, active power control strategy and circulating current suppression strategy are designed to ensure the safe and stable operation of hybrid MMC. Finally, a two-terminal MMC-HVDC model is built with PSCAD/EMTDC. The proposed control strategy is verified by simulations under an unbalanced grid fault. The uninterrupted operation of hybrid MMC is achieved.