Recent droughts have changed meteorological and hydrological conditions of Lake Poyang and caused great influences on vegetation growth, especially for the vegetation biomass on the ground. To investigate the influences of droughts on vegetation, it is vital to preserve habitats for migrating birds and to understand the ecological functionality of wetland. For this purpose, we used long-term satellite data to inspect the response of vegetation biomass associated with field measured vegetation biomass for the typical drought years 2003 and 2006 in terms of vegetation area, biomass density and total biomass. Vegetation area, biomass density and total biomass show general two peaks across 2003 and 2006, and the peaks occur in April and November, respectively. The biomass had little variation by comparison with multi-year mean biomass between 2001 and 2010, while biomass for the second half year of 2006 are much higher than multi-year averages for corresponding months. The dominating factor affecting vegetation area is the lake water level, while biomass density is affected by temperature. The time of water recession has the greatest influence on biomass density variations. The total biomass is affected by both vegetation area and biomass density, and the magnitude of effects of vegetation area is more than that of biomass density. This is more significant for 2006 than 2003. To conclude, response of vegetation to hydrological drought is much stronger than that to meteorological drought in 2006.