The restoration and reconstruction of the degraded riparian vegetation affected by urbanization and human activities have been a hot issue of the ecological environment in recent years. The interspecific relationships of plant communities directly affect the succession and restoration of vegetation. To explore the impact of flooding disturbance on community stability and interspecific relationships in the riparian zone of reservoir, the original riparian vegetation in Danjiangkou Reservoir before the first phase of the Middle Route of the South-to-North Water Diversion Project was investigated. The stability and interspecific relationship of plant communities in the riparian zone under the influence of four different flooding durations were analyzed. Annual average flooding duration was categorized as:those of more than 9 months (below 142 m above sea level), 6 to 9 months (between142 m and 147 m above sea level), 3 to 6 months (between 147 m and 151 m above sea level), and less than 3 months (between 151 m and 157 m above sea level). The stability of plant communities was analyzed by the M. Godron stability measurement method, and the interspecific correlation analysis of dominant species in plant communities under different flood disturbance was conducted by variance ratio, χ² test, association coefficient value, and Spearman rank correlation test. The results indicated that:(1) the order of community stability of riparian vegetation from high to low was:3 to 6 months flooding duration, 6 to 9 months flooding duration, less than 3 months flooding duration, and more than 9 months flooding duration. In a word, the stability of plant community under moderate flooding disturbance was better than the stability of plant community under severe and mild flooding disturbance. (2) There were significantly positive correlations among riparian vegetation of Danjingkou Reservoir at different flooding disturbance. With the increase of flooding duration, the ratio of the positive correlation species to the total species was decreased, the ratio of the negative correlation species to the total species was increased, the ratio of positive and negative correlations species was decreased, and the strength of interspecific association within the community decreased gradually. The results suggested that the interdependence of interspecific association was decreased or the competition of interspecific association was increased within the riparian plant communities along with the increase of flooding disturbance intensity. Based on the results, the spatial distribution and ecological habits of plant species under different flooding duration were discussed. Some suggestions on species selection for vegetation restoration in the riparian zone with different flooding duration were put forward.