This article refers to the adjacent grid method to investigate the aboveground vegetation in the middle section of the Three Gorges Reservoir (Fuling-Fengjie section of Chongqing City). We use niche width, niche overlap, χ² test and other methods to compare the niche of dominant herbaceous plants, which could reveal the ecological characteristics of dominant herbaceous plants in the Three Gorges Reservoir water level fluctuating zone to a certain extent. Then, we infer the succession trend of plant community, so as to provide theoretical basis or reference suggestions for the ecological restoration of vegetation in the Three Gorges Reservoir water level fluctuating zone. The results showed that:(1) There were 57 plant species belonging to 22 families and 44 genera. The niche breadth of bermudagrass was the largest and occupied the absolute competitive advantage. (2) Among the 105 dominant plant species pairs studied, there were 4 species pairs with niche similarity ratio (C_ih) ≥ 0.50 and 7 species pairs with niche overlap value (L_ih) ≥ 0.50, indicating that the similarity between species was small and the competition was weak. (3) χ² test results showed that the positive and negative association ratio of dominant plants was 1.33, indicating that the positive association advantage was not obvious. Pearson and Spearman rank correlation test showed that the positive and negative association ratio was 0.54 and 0.75, respectively, indicating that negative association was dominant. All the three tests showed that the interspecific association of dominant plants was weak, the stability was relatively poor and the independence was relatively strong. (4) The number of species with interspecific association coefficient (AC) ≥ 0.60 was 7 and the number of species with cooccurrence percentage (PC) ≥ 0.7 was only 1, indicating that the positive association between species was not strong and species tended to be independent. (5) Pearson and Spearman rank correlation tests showed a significantly positive correlation with C_ih and L_ih between species, indicating that the stronger the positive (negative) correlation, the greater the C_ih and L_ih. (6) In order to maximize the structural stability and species diversity of plant community in the Three Gorges Reservoir water-level-fluctuating zone, the following suggestions were put forward for vegetation restoration and reconstruction in small watershed:on the whole, a community configuration mode with Bermudagrass, Cocklebur, Bidens, etc. as the dominant plants, and Setaria, Barnyardgrass, and Virginia etc. as the companion species could be used for macro layout. In the local, the configuration mode of Echinochloa crusgalli+Abutilon bicolor, Setaria setifolia+Melilotus lutea, Digitaria tangutorum+Polygonum hydropiper etc. could be used for field configuration.