The fractional level modular multilevel converter (FLMMC) can effectively improve the voltage quality of MMC with small quantities of submodules. However, the switching loss of FLMMC under existing fractional level modulation (FLM) strategy is high. In order to reduce the switching loss of FLMMC, a modified FLM strategy including submodule energy balancing segment and submodule classification inserting segment was proposed in this paper. During the energy balancing segment, both the conventional submodule and the fractional level submodule participated in sorting and inserting at the time of each level change, so as to achieve energy balance between the two types of submodules. During the classification inserting segment, the conventional submodule and the fractional level submodule were sorted and inserted separately according to the integral level or the fractional level, so as to decrease the switching times of power devices. Simulation results based on Matlab/Simulink reveal that the proposed modified FLM strategy can significantly reduce the switching loss of FLMMC, and obtain excellent effect on level multiplying.