Physical model tests are made to study the deformation characteristics of several geogrid-reinforced expansive rocks due to moisture absorption. Research result indicates that obvious expansion deformation takes place in expansive rock under the condition of moisture absorption, which causes soil mass to be damaged due to tensile crack. Geogrids embedded make it possible to obviously decrease the lateral deformation of expansive rock, but have little influence on the vertical settlement of soil. At the same time, geogrids can effectively restrain the occurrence and development of cracks, and alter the development law of expansion deformation of expansive rock. More importantly, geogrids exert significant effect on the transport process of moisture content. This shows that under the condition of one-dimensional infiltration, geogrid-reinforcement makes moisture content more difficultly to infiltrate toward soil mass, the time when moisture content in shallow layer begins to change and keeps stable is longer than unreinforced soil, distribution of moisture content field within reinforced-soil is completely different from that within unreinforced soil.