Abstract: The Bashierxi pluton is located in the western segment of the eastern Kunlun, between Baiganhu fault and Aerjin fault, this pluton mainly consists of monzonitic granite and K-feldspar granite, and the monzonitic granite is closely related with the ore-forming process of the Baiganhu tungsten-tin deposit. The internal structures, cathodeluminescence (CL) images and Th/U ratios of the zircon grains from the monzonitic granite reveal that these zircon grains have typical characteristics of magmatic zircon. The LA-ICP-MS analyses show that the zircon grains from the monzonitic granite have concordant U-Pb ages of (458.0±9.0)Ma, on the other hand, the zircon grains from the K-feldspar granite have U-Pb ages of (432.3±0.8)Ma, these data indicated that the Bashierxi pluton is a intrusion formed from Late Ordovician to Early Silurian. Major and trace element data of the monzonitic granite show that Bashierxi granite is weakly metaluminous or peraluminous A-type granite. These rocks were considered as melts derived from crustal source during back-arc basin extension in eastern Kunlun, and the early Baiganhu tungsten-tin deposit era is represented by the ages of monzonitic granite.