Deep-sea records from ODP Sites 1143 and 1144 in the northern and southern South China Sea (SCS), including foraminiferal delta (super 18) O and delta (super 13) C, opal percentage and pollen percentage, reveal that variations in the east Asian monsoon are closely correlated with variations in the Earth's orbital parameters (eccentricity, obliquity and precession) and global ice volume on an orbital scale. All the monsoonal proxies show strong 100 ka, 41 ka and 23 ka cycles. Although G. ruber delta (super 13) C from Site 1143 is coherent with the ETP (ETP = normalized (eccentricity + obliquity-precession) at eccentricity, obliquity and precession bands, most of the coherent relationship focuses on the precession band. The other monsoonal proxies are coherent with the ETP only at the precession band, which indicates that precession dominates the Pleistocene tropical climate changes. The phase relationship of the monsoonal proxies with foraminiferal delta (super 18) O implies that global ice volume changes have played a significant role in modulating the east Asian monsoon climate, at least dominating the winter monsoon. This forcing mechanism of the east Asian monsoon is apparently different from that of the Indian Ocean monsoon. Variations in the east Asian monsoon at the precession band, at least that of the winter monsoon, have been controlled not only by sensible heating but also by latent heating of surface water in the South China Sea.