Virtual modeling and numerical simulation of microwave equipment and straw powder were carried out by Comsol Multiphysics software to study the effects of wave ports at different positions and multiple wave ports combined on straw powder heating. The experimental results were verified by simulation of the heating conditions of the right port, the right port and the left port open, and the three ports open together. It was found that the heating curve of the experimental temperature measuring point was consistent with that of the simulation, indicating that the model was verifiable. When the wave ports at different positions heated the straw powder separately, the hot spots would appear at different positions, and the heating effect on the material was greatly different. When multiple ports are opened together, the hot spot shape and position of straw powder was changed and the temperature in the central area of the hot spot decreases to some extent. Under the same power, the average heating rate of single port opening is faster than that of multi-port combination. The average heating rate under single port opening on the left side is the fastest, which is more than twice that of single port opening on the right and back side. In the case of multi-port heating, it has an optimization effect on the hot and cold points caused by microwave heating, and the peak of the average temperature gradient is reduced by about 22.7%. In terms of the material heating uniformity, multiple wave ports can be considered to ensure the material heating uniformity, although the energy loss will increase. However, it can be used to improve the heating uniformity of wheat straw in the case of sufficient energy input.