Abstract: Metamorphic intrusions into lower Proterozoic Kemuqi group were found in Kuerti region of Fuyun County, Xinjiang, and were determined for LA-ICP-MS zircon U-Pb ages. According to zircon cathodoluminescence images and Th, U characteristics, the zircons can be classified into magmatic zircons, metamorphic zircons and captured ones. The result shows that the original rock crystallization age is(496.3±6.4)Ma(MSWD = 0.74), and the age of its metamorphism is between 444 Ma and 452 Ma, indicating the rocks were produced in late Cambrian period. Combined with the data of southern margin of Altay, the authors hold that the Paleo-Asia Ocean may start to subduct from late Cambrian. In addition, from the captured inherited magma zircon, the authors obtained the inherited ages from 783 to 901 Ma, implying the existence of Precambrian basement in Altay orogenic belt.