Abstract: Since the outbreak of novel coronavirus pneumonia, the requirements for disinfection and sterilization have been increasing in all walks of life. Therefore, it is of great significance to research the technology of microwave sterilization. In the traditional microwave sterilization technology, due to the uneven heating of solid medium, the sterilization “cold point”appears and the sterilization time is too long. Firstly, the electric field distribution characteristics of the microwave radiation cavity and the temperature distribution characteristics of the solid medium are simulated. The results indicate that the electric field distribution in the microwave radiation cavity shows that the electric field near the source field is greater than that far away, and the temperature of the solid medium is higher around and lower in the middle. Then, a stirrer is added into the radiation chamber to improve the electric field distribution and the temperature distribution of the medium. Finally, through the microwave sterilization test, it is proved that the stirrer can significantly improve the uneven heating in microwave heating sterilization, and increase the sterilization rate.