Plant functional trait is recognized as an effective tool in explaining the adaptive mechanism of vegetation to environmental change. A coniferous tree, Taxodium ‘Zhongshanshan’, is widely planted and grows well in the riparian zone of the Three Gorges Reservoir. However, there are few studies on ecological adaptation of T. ‘Zhongshanshan’ to different water levels in the riparian zone. According to the depth of different water levels, the water-level fluctuation zone was divided into three transects:the shallow submergence (SS) of 171-175 m, the moderate submergence (MS) of 168-171 m, the deep submergence (DS) of 165-168 m, and no flooded (LS). A total of 25-30 T. ‘Zhongshanshan’ trees were randomly selected from each transect to analyze the characteristics and their changes of functional traits across different water levels. A series of plant functional traits were measured at each sample tree, mainly including tree height, the width of leaf epidermis, vane thickness, non-structural carbohydrates and organic acid, etc. Our results showed the leaves in DS showed the xerophytic characters, with smaller stomatal aperture and thicker palisade tissue. The growth of T. ‘Zhongshanshan’ above water level 171 m was significantly better than that below 171 m. The contents of non-structural carbohydrates, soluble sugar, starch, tartaric acid, malic acid and citric acid in roots were higher in MS, but the contents of oxalic acid were the highest in DS. We compared the functional traits in different transects. In SS, the flooding period happened to be the slow growth period of T. ‘Zhongshanshan’, which did not affect tree growth. There were no significant differences in functional traits compared with the control group. In MS, when the water receded in February, the climate was just suitable for the sprout of T. ‘Zhongshanshan’, the water stress decreased and the roots of T. ‘Zhongshanshan’ entered into the recovery stage earlier. The functional changes and responses induced by stress were reversible. The stress was within the limit of its self-regulation ability. The viability of T. ‘Zhongshanshan’ was not greatly affected, and the plants maintained normal growth. Compared with ones in SS, trees in MS grew worse, but their survival rate were all higher. However, the flooding period was 6 months and the high temperature period was 2-3 months in the DS. Trees had been suffered chronic or irreversible damage by water stress. After water withdrawal, the root system could not recover normal metabolism quickly. The growth period of the plants was short and its vitality became fragile. With the increase of the flooding frequency, the plants were easy to die. Although the height and size of the plants were not significantly different from those in MS, the survival rate was low. Therefore, the habitat with water level above 168 m was suitable for planting T. ‘Zhongshanshan’.