Abstract: In high power traction drive systems, the switching frequency is very low, so the multi-mode modulation strategy is used to optimize current waveform in the whole speed region. In order to solve the current shock and torque fluctuation in the process of multi-mode modulation switching, the motor stator flux linkage during switching was studied, and a multi-mode modulation switching strategy based on pulse insertion method was proposed. In this strategy, the stator flux linkage deviation was accurately compensated by inserting pulses, so the continuity of stator flux linkage trajectory before and after switching can be ensured, and then the smooth switching of modulation mode was realized. This method has good universality because it can switch at any sampling point and not be affected by motor parameters and modulation mode. The validity and effectiveness of this strategy has been verified by simulation and experimental results.