Bidirectional power converters, which serve as the core components for mutual energy transfer between the energy storage system and the DC bus in DC microgrid, require appropriate commutation strategies to determine their power flow direction. However, the resonant converter is prone to oscillations near no-load, which can easily lead to mis-commutation of the converter. The article proposes a commutation operation control strategy based on the judgment of voltage fluctuation and current drop trend, and designs the voltage and current threshold parameters during switching to optimize the switching effect, which can accurately find the switching moment point according to the load condition when the converter is running in forward and reverse directions, and it is not easy to occur mis-commutation. The test results verify the effectiveness of the switching control method.