Abstract: After preliminary screening by a team from the Chinese Research Academy of Environmental Sciences, three emergent plants suitable for ecological restoration were identified in the riparian zone of Lake Taihu, including Zizania latifolia, Thalia dealbata and Sagittaria trifolia. The emergent plants have high requirements for the water depth and excessively high or low water depths will inhibit the growth of emergent plants. To investigate the response of emergent plants to water depth, this study used high water depth (40 cm), medium water depth (20 cm) and low water depth (10 cm) treatments and measured the above- and below-ground morphological traits (above-ground dry mass, below-ground dry mass, leaf area and root length), relative growth rate (RGR), and physiological parameters (total soluble sugar, superoxide dismutase (SOD) and malonic dialdehyde (MDA)) of the three emergent plants. The effects of different water depths on the traits of these emergent plants were determined after 42 d. The results show that: (1) Different water depths significantly affected all traits of the emergent plants. Relatively high and low water depths affected the above- and below-ground morphological traits, RGR and physiological parameters, and the emergent plants adapted to and resisted the negative effects from water depth stress by regulating these traits. (2) Under the stress of high water depth, the three emergent plants tended to produce higher total soluble sugars, SOD and MDA, indicating physiological adaptation to high water depth stress. (3) High water depth inhibited S. Trifolia growth, T. dealbata was more tolerant to water depth than S. trifolia, and Z. latifolia was the most water depth-tolerant plant. This study indicates that different plants have distinct adaptations to water depth, and different plant assemblages should be used to resist water depth changes in the ecological restoration projects.