The historical data of phytoplankton and chlorophyll a(Chl a)(1990–2002)obtained during the Chinese National Antarctic Research Expedition(CHINARE)in the Prydz Bay have been integrated.The results showed that the temperature,salinity,nutrients,and oxygen of seawater changed when El Nino/La Nina occurred.The variation of biological communities reflected the response of ecosystem to environmental changes.During El Ni?o period,Chl a concentration and phytoplankton community structure changed significantly,and the relative proportion of diatoms increased while dinoflagellates decreased.During La Ni?a period,the proportion of diatoms decreased,but the golden-brown algae and blue-green algae increased significantly.The variation of phytoplankton population directly affected the biodiversity of the bay,which were also quite sensitive to the marine environment changes.Meanwhile,the satellite remote sensing data of 2002–2011(December–March)have been used to study the temporal connection change of Chl a and phytoplankton in the Prydz Bay.We found that there were significant differences in the monthly variation characteristics of satellite remote sensing Chl a and sea surface temperature(SST),which had some links with sea ice melting and El Ni?o/La Ni?a events.We found that the start time of bloom advanced,lagged or synchronized with the changes of the SST,and we also found the occurrence time of phytoplankton bloom corresponded with the sea ice melting inner bay.To some extent,this study will help us understand the relationships between ENSO events and the phytoplankton bloom in the Southern Ocean. The historical data of phytoplankton and chlorophyll a (Chl a) (1990-2002) was obtained during the Chinese National Antarctic Research Expedition (CHINARE) in the Prydz Bay have been integrated. The results showed that the temperature, salinity, nutrients, and oxygen of seawater changed when El Nino / La Nina occurred. The variation of biological communities reflected the response of ecosystem to environmental changes. Duration El Niño period, Chl a concentration and phytoplankton community structure changed significantly, and the relative proportion of diatoms increased while dinoflagellates decreased.During La Niña period, the proportion of diatoms decreased, but the golden-brown algae and blue-green algae increased significantly. The variation of phytoplankton population directly affected the biodiversity of the bay, which were also quite sensitive to the marine environment changes. While while the satellite remote sensing data of 2002-2011 (December-March) have been used to study the temporal connection c hange of Chl a and phytoplankton in the Prydz Bay. We found that there were significant differences in the monthly variation characteristics of satellite remote sensing Chl a and sea surface temperature (SST), which had some links with sea ice melting and El Niño / La Ni? A events. We found that the start time of bloom advanced, lagged or synchronized with the changes of the SST, and we also found the occurrence time of phytoplankton bloom corresponded with the sea ice melting inner bay. To some extent, this study will help us understand the relationships between ENSO events and the phytoplankton bloom in the Southern Ocean.