Abstract: The research progress on the microwave sintering mechanism of metal powders was reviewed in this paper from the aspects of the electromagnetic effect on metal powders in microwave field and the sintering behavior of metal powders in microwave field. In the electromagnetic effect, the influences of thermal effect and non-thermal effect on sintering behavior were introduced, respectively. The thermal effects of sintering mainly included the electromagnetic power loss caused by microwave heating and the electromagnetic focusing phenomenon. The non-thermal effects mainly included the microwave discharge effect and the magnetic effect. In the sintering behavior, the material migration mode and the growth mechanism of sintering neck during the growing process were reviewed, the material migration mode was influenced by the material type and process parameter, and the growth of sintered neck was closely related to the temperature field and electromagnetic field. Based on the review of current research progress, the shortcomings and deficiencies were analyzed, and the future research direction of the microwave sintering mechanism was also proposed.