Abstract: Jiujiang Station, Hukou Station and Datong Station are three crucial hydrological stations in the lower reaches of the Changjiang River.Analyzing their runoff relationships, wetness-dryness evolutionand encounter characteristics is of great significance for identifying multi-dimensional runoff relationships in the lower reaches of the Changjiang River.Based on the sliding correlation coefficient method, we analyzed the time-varying characteristic of multi-dimensional runoff correlations in the lower reaches of the Changjiang River.Then we constructed a joint distribution of multi-dimensional runoff and runoff evolution in the lower reaches of the Changjiang River based on the Copula theory, and analyzed the wetness-dryness evolutionand encounter characteristics.The results show that the time-varying intensity of runoff correlation is the highest in Jiujiang-HukouStation, followed by Hukou-Datong Station, and the minimum is Jiujiang-Datong Station.The runoff at each station has a high synchronization of wetness-dryness state, the highest isJiujiang-Datong Station, followed by Hukou-Datong Station, the lowest isJiujiang-Hukou Station, while theasynchronous feature of wetness-dryness state is reverse.The periods with the highest synchronization rates of wetness-dryness state for Jiujiang-Hukou Station, Jiujiang-Datong Station and Hukou-Datong Station are non-flood period, flood period, and non-flood period, respectively.The self-change and mutual change probabilities of runoff wetness-dryness state at each station are relatively stable, and there are no extreme situations at present.The annual runoff and flood period runoff at Jiujiang and Datong Stationare most likely to be in the wetness-dryness mutual changestate, and the runoff in non-flood period is most likely to be in the continuous wetness and continuous dryness state.While the annual runoff and the flood periodrunoff of Hukou Station is most likely to be in the continuous wetness and continuous dryness state, and the runoff in non-flood period is most likely to be in the mutual wetness-drynesschange state.The research results can provide theoretical references for the analysis of multi-dimensional runoff relationships in the lower reaches of the Changjiang River.