Abstract: The Hangzhou Bay coastal wetland, a critical stopover site along the East Asian-Australasian Flyway (EAAF), has been increasingly affected by rapidly expanding human reclamation activities in recent years. Utilizing long-term waterbird monitoring data (2017—2024), this study investigated the species richness, threatened species composition, and abundance of waterbirds across three habitat types: tidal flats, wetland parks, and pond wetlands. The conservation value of coastal wetlands in the Hangzhou Bay was evaluated, and the formation and maintenance mechanisms of waterbird community diversity were explored through analyses of bird community assembly (from functional and phylogenetic perspectives), dominant group dynamics, and ecological factor correlations. The results showed significant differences in species, functional, and phylogenetic diversity among waterbird communities in the three habitat types. Both the Shannon-Wiener index and the Simpson diversity index of waterbirds in tidal flats were significantly higher than those in wetland parks (p<0.05) and pond wetlands (p<0.01). Additionally, tidal flats exhibited the highest waterbird diversity conservation value index. In wetland parks and reservoir-pond wetlands, the functional and phylogenetic communities of Anatidae (ducks and geese) were clustered, particularly in wetland parks, where environmental filtering dominated community assembly. Correlation analysis revealed that the Normalized Difference Vegetation Index influenced the functional and phylogenetic diversity of shorebirds (Charadriiformes) in both wetland parks and tidal flats. It is also found the Hangzhou Bay coastal wetland consistently met all three waterbird-related criteria under the Ramsar Convention, demonstrating international significance in terms of waterbird abundance, threatened species presence, and the EAAF 1% threshold. To mitigate the impact on avian diversity, future management strategies for the Hangzhou Bay coastal wetland should consider adjusting vegetation coverage appropriately.