Abstract: The thermal history of the southern South China Sea (SCS) exhibited a reducing tendency since Pleistocene. The temperature profile is characterized by a cooling trend during glaciations but remains steady during interglaciations. Meridional thermal gradient between southern and northern SCS reflects the Eastern Asian Winter Monsoon (EAWM) change. Thermal gradient history during the past 2 Ma indicated that EAWM was strengthened before mid-Pleistocene and weakened since then, but restrengthened in the later Quaternary. This long term trend is superimposed by orbital glacial cycles with the EAWM stronger during interglaciations and weaker during glaciations. Tectonic uplifting of the Tibetan Plateau may have important influence on the strengthening of EAWM in the mid-Pleistocene. Global ice volume and ENSO changes may be the main reasons for the overall trend and the orbital cycle of EAWM.