The periodic impoundment of the Three Gorges Reservoir has significantly changed the composition and diversity of plant communities in the water-level-fluctuation zone (WLFZ), and its succession process can reflect and influence the changes of the whole reservoir bank ecosystem. At present, there is still a lack of long-term continuous observational records. Based on the monitoring data of fixed sample sites from June 2009 to June 2021 and leaf functional traits of dominant plants, this study analyzed the change trend of plant community diversity and the important value of dominant plants at the altitudes of 145-155 m, 155-165 m and 165-175 m in the WLFZ, and revealed the influence of reservoir operation characteristic parameters and meteorological factors on plant characteristics in the WLFZ through redundancy analysis. The results showed that: 1) dominant plants varied obviously in different elevation areas. The dominant species exhibiting higher important value (IV) at the altitude of 145-155 m and 155-165 m were Cynodon dactylon, Cyperus rotundus and Xanthium sibiricum with the higher water-tolerant capacity, while C. dactylon, Daucus carota and Bidens pilosa were dominant at the altitude of 165-175 m. The Shannon-Wiener diversity index of plant communities (1.47±0.47) and the Pielou index (0.67±0.07) at the altitude of 145-155 m were significantly lower than those at the altitude of 165-175 m. 2) From 2009 to 2021, the Shannon-Wiener diversity index and Pielou index at the elevation of 145-155 m and 155-165 m decreased, while the importance value of C. dactylon and C. rotundus increased. 3) RDA analysis showed that the flooding time, number of periodic flooding and elevation can significantly affect the IV of dominant plants. The IV of species such as C. dactylon, A. philoxeroides and X. sibiricum were positively correlated with number of periodic flooding. The IV of Setaria viridis and Polygonum hydropiper were negatively correlated with number of periodic flooding. With increasing elevation, the IV of D. carota, B. pilosa and Artemisia annua increased, however, the IV of C. dactylon, C. rotundus and P. hydropiper declined. 4) The adaptation strategies of different plants varied. Specific leaf area (SLA) of C. dactylon (32.8±7.2) mm²/mg was the largest, followed by B. pilosa (30.6±3.9) mm²/mg and X. sibiricum (30.0±3.0) mm²/mg. The SLA of these plans in the WLFZ were lower than those of plants in the unflooded area. 5) The investment proportion of S strategy of C. dactylon was 53.4% with high flooding-resistant ability. The investment proportion of C strategy of X. sibiricum was 61.3% with the largest leaf area. The proportions of R strategy of Comnyza canadensis and B. pilosa were 64.6% and 50.9% that have a lot of small seeds. The proportions of R strategy of A. philoxeroides was 71.3% with developed roots. The results of this study may deepen the scientific understanding of the change trend of plant communities and the ecological adaptation strategies of dominant plants in the WLFZ of large reservoirs.