Abstract: Located in the westerly region，Lake Barkol is the ideal research area of the paleoclimate and environment evolution. Based on the multi-proxy analysis of BLK-1 profile, the climate and environmental changes over the past 9000 is established. Arsenic is a poisonous element in nature, which comes mainly from the surrounding bedrock and is brought into the lake by wind after the physical weathering. The research has shown that higher Arsenic values could reflect relatively cold and arid conditions, vice versa. Moreover, arsenic is also a good indicator of the abrupt climate events in Barkol lake during the Holocene. Arsenic is so sensitive that its deposition rate is similar with other elements in the wet period but has an obvious change in arid period. We suggests that the arsenic has valuable potential to indicate past climatic changes in the westerly-influenced arid region. The research about the source of arsenic is conducive to the study of paleoclimate and the prevention of arsenic pollution.