Abstract: Upon simulation of soil water change of hydro-fluctuation belt in Three Gorges Reservoir Area, four different kinds of water treatment were applied to study the photosynthetic eco-physiological characteristics of Taxodium ascendens seedlings under the environment of hydro-fluctuation belt. Four kinds of water treatment were normal growth water condition (CK) , light drought stress (T1) , soil water saturation (T2) and soil submersion (T3). The results showed that different water treatments could effectively influence the content of photosynthetic pigment, leaf gas exchange and apparent resources use efficiency of Taxodium ascendens seedlings. It was also demonstrated that the Taxodium ascendens seedlings could not only tolerate water submersion and wet condition but also endure a certain degree of drought. To establish protection forest system of hydro-fluctuation belt in Three Gorges Reservoir Area, the species Taxodium ascendens was suitable to be planted in conditions of root submersion or saturation soil water. In case planted in drought soil condition, this tree species should be watered appropriately in order to keep its normal net photosynthetic rate.