ABSTRACT Due to its small size, microchannel heat exchangers are widely used in fine engineering fields such as electronic equipment. In this paper, the boiling heat transfer characteristics of refrigerants and nanofluids in microchannels are studied by applying electric fields, magnetic fields, and electromagnetic synergistic fields. Compared with deionized water, using R141b refrigerant with a boiling point of only 32.1°C as the base liquid can better achieve two‐phase flow boiling heat transfer. The results show that the addition of magnetic nanofluids can significantly improve the heat transfer efficiency, and the heat transfer efficiency is greatly improved by applying electric and magnetic fields at the same time. Compared with pure refrigerant, the application of electric field and nanofluid can increase the average heat transfer effect by 17% and 9%, respectively, within the full load range, while applying electric field and magnetic excitation, respectively, on the basis of nanofluid can bring about the improvement effects of 24% and 29%. After applying electromagnetic synergistic excitation to the nanofluid, the average heat transfer enhancement effect within the full load range reaches 36%.