Abstract: We conducted monthly waterbird surveys using random transects in Beili and Houshui Bays, Hainan Island from November 2004 to November 2005. Fifty waterbird species of 5 orders and 10 families were recorded. The waterbird species richness and abundance were the highest in November and the lowest in June. The abundance of waterbirds was correlated among species and affected seasonal dynamics and species richness. Asian dowitcher (Limnodromus semipalmatus) was recorded for the first time in Hainan Island. The endangered black-faced spoonbill (Platalea minor) occurred at the study sites from September to April. The highest number (75) of this species was observed in Beili Bay in December while the largest flock (9 in-dividuals) was present in Houshui Bay in January and February. The Shannon-Wiener index and Pielou index were higher in Beili Bay than in Houshui Bay. Differences in area and habitat heterogeneity between the two sites probably affected observed variation of waterbird community structure. Human disturbance might be an important factor altering wintering habitat of black-faced spoonbill. The results suggest that Beili and Hou-shui Bays are important wintering site of many waterbirds, particularly black-faced spoonbill; long-term monitoring and conservation programs should be considered.