Abstract: There exists garnet-bearing muscovite-biotite plagioclase gneiss in western kangxiwar fault. According to cathodoluminescence (CL) images and Th, U, REE characteristics, the zircons can be classified into magmatic zircons and metamorphic-hydrothermal ones. Zircon LA-ICP-MS U-Pb dating shows that the age of the protolith of the garnet-bearing plagioclase gneiss is 254.5Ma±4.2Ma (MSWD=0.16), and the age of its metamorphism is 242.7Ma±2.3Ma(MSWD=0.11). In combination with regional geological information, the authors hold that the metamorphism of garnet-bearing plagioclase gneiss was related to the collision and orogeny of Paleo-Tethys, suggesting that the Western Kunlun orogenic belt was still in the period of Paleo-Tethys collision in early Middle Triassic.