Hydrological connectivity is a key factor affecting hydrological processes and the ecosystem structure and function in the floodplain areas, and is particularly crucial for the growth and distribution of wetland vegetation. This study utilizes high spatiotemporal resolution NDWI (Normalized Difference Water Index) (8d, 30m) and EVI (Enhanced Vegetation Index) (16 d,30 m) datasets, reconstructed using the ESTARFM model (Enhanced Spatial and Temporal Adaptive Reflectance Fusion Model), to analyze the Poyang Lake floodplain system from 2000 to 2022. By combining these datasets with geostatistical connectivity functions and applying correlation analysis, we systematically investigated the evolution characteristics of multidimensional hydrological connectivity and its impact on wetland vegetation growth. The results revealed several important discoveries: 1) Poyang Lake's hydrological connectivity varies significantly with increasing distance across different hydrological periods, displaying dynamic changes in both the east-west (E-W) and north-south (N-S) directions. The rate of change in hydrological connectivity function follows this pattern: dry period>recession period>rising period>flood period. In other words, low hydrological connectivity can be observed during the dry period, intermediate hydrological connectivity tends to occur during the rising and recession period, while high hydrological connectivity is found during the flood period. 2) During the study period, the N-S hydrological connectivity of the Poyang Lake was notably higher than the E-W hydrological connectivity. However, this dominance varied across different regions. For instance, in the main lake region and the Nanji Wetland National Nature Reserve, the dominant hydrological connectivity shifted over time. Conversely, the dish-shaped lake region and the Poyang Lake National Nature Reserve consistently exhibited N-S hydrological connectivity dominance. What's more, although the E-W hydrological connectivity showed a consistent downward trend, the N-S hydrological connectivity exhibited substantial variability over time in different regions. 3) Significantly negative correlation was observed between wetland vegetation EVI and hydrological connectivity in the Poyang Lake floodplain. At the interannual scale, the wetland vegetation EVI in the main lake region is predominantly influenced by the E-W hydrological connectivity, while the vegetation EVI in the dish-shaped lake region and the Poyang Lake National Nature Reserve is jointly affected by both the E-W and N-S hydrological connectivity. The vegetation EVI in the Nanji Wetland National Nature Reserve is more affected by the N-S hydrological connectivity. Strengthening research on the impact of hydrological connectivity on the "structure-process-function" of wetland ecosystems under the changing environment is vital for promoting water resource management and wetland ecological protection in lake systems.