Hybrid MMC consisting of full-bridge sub-modules (FBSMs) and half-bridge sub-modules (HBSMs) works as the HBSMs mode during normal operation. The charging behaviours of FBSMs and HBSMs are almost coincident. The loss distribution of sub-modules device is extremely uneven, eespecially the loss of IGBTs at the lower part of HBSMs is particularly prominent for MMC works as an inverter, which threatens the operation safety of the system. Thus, a loss distribution optimization method with the differential control of FBSMs and HBSMs is proposed. Firstly, the reason of loss imbalance is clarified by calculating the sub-module device loss. Secondly, to improve the device loss distribution, a full-bridge /half-bridge modules decoupling control method without affecting the external characteristics of the equipment output is proposed. Then, the influence mechanism of modules average switching function on the device conduction and switching losses is analyzed. Aming to reduce the IGBT loss in the lower part of HBSM, the optimal modules average switching function is derived. Finally, the feasibility of decoupling control strategy and the effectiveness of loss distribution optimization are verified by MATLAB/Simulink and PLECS simulation.