Based on the stable isotopic analysis of more than 1000 samples of planktonic and benthic foraminifers from ODP Site 1148 in the northern South China Sea (SCS), the oxygen iso tope stratigraphy has been applied to the last 3 million years for the first time in the SCS. Further more, the paleoceanographic changes in the northern SCS during the last 6 million years have been unraveled. The benthic foraminiferaδl8O record shows that before ～3.1 Ma the SCS was much more influenced by the warm intermediate water of the Pacific. The remarkable decrease in the deepwater temperature of the SCS during the period of 3.1-2.5 Ma demonstrates the forma tion of the Northern Hemisphere ice-sheet. However, the several sea surface temperature (SST)reductions during the early and middle Pliocene, reflected by the planktonic foraminiferal δ18O,might be related to the ice-sheet growth in the Antarctic region. Only those stepwise and irreversi ble SST reductions during the period of ～2.2-0.9 Ma could be related to the formation and growth of the Northern Hemisphere ice-sheet.