AAbstract Spores, pollen, freshwater algae and dinoflagellate cysts in the OligocenePliocene of Well LS33-1-1 and Well LS2-1-1 from the Southeast Hainan basin, South China Sea were analyzed. The results disclosed the changes of paleovegetation,paleoclimate and depositional paleoenvironment. The vegetation during the formation of the Yacheng and Lingshui Formations was tropical, subtropical evergreen broadleaved forest and evergreen broadleaved-coniferous mixed forest, suggesting a relatively cool and humid climate condition. The Sanya Formation witnessed the vegetation of tropical, subtropical evergreen forest and evergreen broadleaved mixed forest,indicating that the climate was warm and humid. The period of the Meishan Formation was a transition of climate change. Vegetation of the Huangliu Formation was subtropical evergreen broadleaved and coniferous mixed forest and the climate was cool and dry. With the increase of herb pollen in the top layer, the Yinggehai Formation confirmed that the climate was cool and dry. The trend of climate change recorded in the OligocenePliocene of the Southeast Hainan basin shared the same characte-ristic of the global climate change. Depositional environment of the study area during the Oligocene might be a costal shallow sea,while during the formation of the Meishan Formation it might evolve to a shelf condition.