Outstanding interfacial mechanical property and its characterization methods are the most challenging problems in microwave curing fiber/epoxy composites. In this study, a new microwave curing process was proposed by introducing the vibrational energy field. Single fiber push-in tests were conducted on both the conventional microwave process and the vibration-microwave process at different heating rates to evaluate the interfacial strength between fibers and resins. To give a detailed illustration of the mechanical test results, microscopic analyses were used to reveal the mechanism of vibration treatment and different heating rates. The results showed that vibration treatment can effectively increase the interfacial shear strength (IFSS) of samples cured by the microwave process at different heating rates by more than 15%, which provides a useful guideline for improving the quality of the microwave-cured composites. Moreover, the values of the IFSS of all samples declined with the increment in the heating rate, which means that excessive heating rate might diminish the properties and quality of composites.