Iron plaque commonly forms on the surface of hydrophytes roots. The amount of iron plaque on the root surface depends on rhizosphere Fe₂₊ concentration and oxidative power of plant roots. Alternate drying and wetting technique has been widely used in the agriculture production. During the processes of drying and wetting, variations of soil moisture and oxygen content resulted in changes of soil physical, chemical and biological properties in rhizosphere, which influenced the formation of iron plaque. Impacts of drying-wetting cycles on rhizospheric characteristics were summarized in this paper. The chemical components and spatial structure of iron plaque were analyzed. The process of iron plaque formation and the factors affected the formation of iron plaque were also discussed. Based on the above discussion, the possible mechanisms for iron plaque formation as influenced by drying-wetting cycles were proposed. Finally the methods for studying iron plaque formation and its application in future were prospected.