As the largest temperate arid region, Central Asia has been attracting widely attention for its great impacts on global climatic change. Global cooling, Tibetan Plateau uplift and the retreat of the Para-Tethys Sea have been thought to be the key factors controlling the formation and evolution of the aridity of the Asian inland. However, most of the existed evidences on this issue are indirect,largely from the eolian records of the surrounding areas, and little from inland arid area. Due to the scarcity of long-term palaeoclimate records, which of these factors playing the major role keeps unclear. Therefore,obtaining a series of direct and convincing climate evidence is of great significance for us to understand the process and mechanism of Asian aridity. Qaidam Basin, the largest closed basin in the northern Tibetan Plateau, develops continuous Cenozoic sediments,which recorded the tectonic uplift of surrounding mountains and climatic evolution of the area. Here we present multiple geochemical climatic proxy records (CaCO_3,SO_4~(2-) and Cl~-) from the Late Cenozoic sedimentary sequence of the Huaitoutala section (37°13'48"N, 96°43'10"E), which is located in the northeastern Qaidam Basin (Fig.l) and consists of the Shangyoushashan Fm., Shizigou Fm. and Qigequan Fm. at ca. 15.3 ~ 1.8Ma (Fang et al.,2007). The analysis results of the climatic proxy records from 663 samples reveal an evident three-stage climate change since the Middle Miocene (Fig. 2). From 15.3Ma to 13.0Ma (relatively humid), the CaCO_3 contents (average 11.331%) showed an upward decrease, as well as the average concentrations of the soluble anions SO_4~(2-)(average 1.464mg/g) and Cl~- (average 12.786mug/g) remained at relatively low values. From 13.0Ma to 6.6Ma (semi-arid and semi-humid), the CaCO_3 contents (average 10.443%) decreased after a sharp increase with superimposed high-frequency fluctuations, while the concentrations of SO_4~(2-) (average 1.526mg/g) and Cl~-(average 17.394mug/g) stepwise increased and an obvious drop occurred at 8.1Ma and lasted to 6.6Ma. Since 6.6Ma (arid), the average contents of all the salinity ions were higher than before, among which the CaCO_3 contents (average 11.908%) displayed stable changes, the concentrations of SO_4~(2-) (average 2.055mg/g) and Cl~-(average 20.314mug/g) showed an evident increase, especially after 2.6Ma. With biological characteristics and previous research (Fig.3 and 4), it is concluded that the Qaidam Basin has experienced increased aridity since ca.13.0Ma,and the extreme aridity was initiated at 6.6Ma. We suggest that the Miocene global cooling exerted a significant influence on the drying of the Qaidam Basin. In addition, the episodic and persistent uplift of the NE Tibetan Plateau since the Late Micocene exerted an important influence superimposed upon this driving force.