The impacts of climate change are particularly striking on Antarctic marine ecosystems,due to the sensitivity of phytoplankton to sea-ice retreat and to minor temperature increases. The sensitivity of Antarctic marine ecosystems to climate change can be exposed by the significant variation in the marine phytoplankton biomass and community structure. In the Antarctic Prydz Bay,the marine phytoplankton biomass and community structure changes significantly impact the marine biological pump and CO_2 absorption in the Southern Ocean. The sedimentary biomarkers (brassicasterol,dinosterol and alkenones),which indicate individual algae (diatoms,dinoflagellates and coccolithophores),were determined by GC (gas chromatography),and were used to reconstruct the historical changes in the phytoplankton biomass and community structure. The data,combined with field and remote sensing Chla (chlorophyll a) and SST (sea surface temperature) data collected in 2001- 2011,were employed to reveal the spatial and temporal variations of the phytoplankton biomass and the impact factors in the bay. The results showed that,over the past century,the phytoplankton biomass indicated by three biomakers (from 212. 04 to 759. 10 ng/g) and w (diatoms) ratio indicated by brassicasterol (from 62. 28% to 87. 13%) increased, while w(dinoflagellates) ratio indicated by dinosterol and w(coccolithophores) ratio indicated by alkenones (from 10. 09% to 27. 98% and from 1. 97% to 9. 74%,respectively) decreased. Therefore,the phytoplankton community structure variation could impact the global carbon cycle by changing the CO_2 absorption in the Southern Ocean and affecting global warming. The phytoplankton biomass indicated by the sea waterrho(Chla) and the sedimentary biomarker records showed significant spatial and temporal patterns in the Prydz Bay and adjacent areas.The indices decreased from the continental shelf of the bay to the continental slope and to the deep sea off the bay. The annual variation in rho(Chla) was similar to SST: the rho(Chla) (1. 69 and 2. 31 mg/m~3) and SST (-0. 30 and 0. 01℃) were significantly high in 2002- 2003 and 2009- 2010,while they were significantly low in 2001- 2002 and 2010- 2011 (1. 08 and 0. 79 mg/m~3,- 1. 19 and - 0. 95℃,respectively). The results indicate that the growth of phytoplankton was significantly impacted by the SST variation in the bay. Further work is necessary to explore the mechanism of variation in the marine phytoplankton biomass and the community structure to climate- driven SST and ocean CO_2 absorption change in the Antarctic area.