Water is one of the main factors causing the deterioration of brick and stone cultural heritages. Thus, clarifying the distribution and movement pattern of water inside these objects has been an important task in conservation studies. Though microwave technology shows good prospects for detecting the moisture content of these materials, it has not been widely adopted in this field. Based on this, our paper first introduces the theoretical foundation of microwave technology and the related devices. The Yuhuang Temple in Shanxi Province was then chosen as a site for measurement of the moisture content of brick and stone material, both in the laboratory and in situ. The results show that microwave technology can accurately reveal the spatial distribution of moisture inside the object, and thus can play an important role in researching the causes of various diseases. In addition, compared to some other nondestructive testing technologies, microwave technology is more advantageous in detecting the moisture content of the material. Thus it is worthy of being studied and applied by cultural heritage researchers and conservators.