Under the background of global cooling during Cenozoic,the main feature of Asian environmental change is the formation and evolution of Asian Monsoon. The Weihe Basin, known as the Weihe graben Basin or Guanzhong Plain,is located in the middle of Shaanxi Province and between Qinling Mountains and the Weibei Mountains. The Weihe Basin has a continuous Cenozoic sedimentary sequence, which provides an excellent archive for studying history of vegetation evolution and exploring the characteristics of the Asian monsoon variation in Cenozoic. Tertiary strata of the Weihe Basin are composed of Honghe,Bailuyuan,Lengshuigou,Koujiacun,Bahe,Lantian and Sanmen formations. We use the pollen data of Xiangcheng Formation in Lushi Basin as an equivalent of Honghe Formation to reconstruct vegatation of Middle to Late Eocene. The data of Xiangcheng Formation, Bailuyuan Formation,Lengshuigou Formation,Lantian Formation and Sanmen Formation are from previous studies and data of Bahe Formation is from our study. By analyzing and integrating the pollen data, this paper reconstructs the paleovegetation and paleoclimate change of the Weihe Basin in Cenozoic. The vegetation was deciduous broad-leaved forest containing tropical and subtropical trees in Middle to Late Eocene, which indicate the climate was very warm and wet. During the Oligocene, vegetation was a deciduous broadleaf forest containing some evergreen tree species, the climate was warm and wet. The vegetation was mainly deciduous broad-leaved tree and the climate was warm and humid during the Early Miocene. In the Late Miocene, vegetation was mainly forest and grassland, and the temperature and precipitation were slightly lower than the Early Miocene. The vegetation was deciduous broad-leaved forest and coniferous mixed forest during the Pliocene. In the Late Pliocene, the climate shifted to dry and cool. Since the Early Pleistocene, the vegetation was replaced by the forest and grassland, the steppe and forest, and the grassland. During the Eocene, tropical plant species were grown in the Weihe Basin. The tropical and subtropical trees decreased slightly during the Oligocene, and the temperature and precipitation decrease compared with the Eocene. The vegetation in Miocene was non-tropical, containing a small number of subtropical trees, and the climate was warm and wet. The vegetation of the Pliocene contains a very small number of subtropical heat-loving trees, which indicate the climate was warm and humid, and the climate was dry at the end of the Pliocene. In the Quaternary, the climate was general dry, and accompanied by significant changes in temperature during glacial-interglacial alternations. In the Cenozoic era, the monsoon precipitation decreased gradually, which was consistent with the global cooling trend. All of these observation reveal the global cooling might be a major driver for the phase weakening of Asian monsoon at tectonic time scale.