In order to analyze the effect of sub-trajectory based overmodulation and limit trajectory superimposed overmodulation output, a simulation model of the two overmodulations is built using Matlab/Simulink, and the voltage utilization efficiency and total harmonic content (THD) of the two overmodulated outputs are compared and analyzed. The results show that the fundamental voltage based on sub-trajectory overmodulation is closer to the input reference, and the total harmonic content of the whole process is lower than that based on limit trajectory superposition overmodulation.