Abstract: Influenced by Three Gorges Reservoir operation mode of “storing the clear water and releasing the muddy water” , the falling zone has developed in the Three Gorges Reservoir area, which covers 348.93 km² areas. And owing to the typical characteristics of alternation of submergence and emergence and wide change extent of water level, the falling zone has complicated ecological characteristics. At meanwhile, this characteristics, to identify the ecological characteristic of vegetation in wet-dry zone, this characteristics plays an important role to ecological restoration project in the falling zone. On the basis of this, this paper selected the falling zone in Zhongxian Shibaozhai of ZHONG county as a study case to analyze the vegetation ecological characteristics. Firstly, ecological diversity index (EDI) was used to analyze the spatial distribution pattern of vegetation ecological diversity. Secondly, canonical correspondence analysis (CCA) was adopted to find the correlation between environmental factors and typical ecological characteristic. Then, by CCA analysis, key environmental factors, which influence the vegetation ecological characteristics, were found in this study. The result shows: with the change of slope height, the EDI of vegetation in the falling zone presents spatial heterogeneity ； there have two turning points in the position of 150 m and 160 m ； there exist remarkable positive correlations among vegetation distribution and soil water content, soil thickness, and negative correlations among vegetation distribution and altitude, river distance.

Key words:  Three Gorges Project  ,   falling zone  ,   ecological characteristic , ecological diversity index , canonical correspondence analysis