Because of the water-swelling properties of clay minerals and the poor cohesion between soil particles, surfaces of earthen sites are prone to deterioration such as spalling and powdering. Chemical consolidation, is an important protective measure against these kinds of deterioration, and although it has some achievements, its overall application is still limited due to its short aging period of materials and the difficulty of reprocessing. In view of this situation, this paper discusses a new protective measure—open microwave reinforcement. Microwave can change the microstructure of clay minerals through thermal and non-thermal effects, thereby enhancing their resistance to environmental effects. Moreover, with the advantages of accurate positioning and controllable energy, microwave can avoid the hazards to the soil and environment brought by chemical material volatilization, so it can safely and effectively consolidate the soil body and thus has a good effect. This paper also discusses the key technologies in the research and development of microwave equipment for strengthening earthen sites, including the determination of equipment parameters and the selection of frequency and auxiliary heat materials.