Road icing in winter brings challenges to traffic safety, and microwave heating and deicing technology is an effective method with the advantages of high efficiency and environmental protection. Magnetite has been widely used as a microwave-absorbing material in pavement. In this paper, magnetite powder formed by crushing natural magnetite and high-purity Fe3O4 powder after purification were mixed to replace mineral powder, and the magnetite aggregate was used to replace the limestone aggregate with the same particle size to enhance the asphalt mixtures’ microwave absorption capacity. The effect of microwave heating time and microwave power on the heating of the asphalt mixtures was studied, and the heating performance of different thicknesses of the asphalt mixtures under microwave radiation was evaluated. The heating performance of the mixtures under different initial temperatures and ice layer thicknesses was also assessed. The results showed that the addition of the magnetite powder–Fe3O4 powder and the magnetite aggregate significantly enhanced the heating performance of the asphalt mixtures by microwave heating. The replacement of the magnetite powder–Fe3O4 powder, the microwave heating time, and the microwave power had positive effects on the heating efficiency of the asphalt mixtures. Moreover, the thinner asphalt mixtures had a better heating performance. The heating and deicing performance of the mixtures decreased with a decline in initial temperature. As the ice thickness increased, the deicing time of the specimen surface to reach 0 °C also increased.