Abstract: Aermantai ophiolite lies in the east of Junggar and has recorded tectonic evolution of the paleo-Asian Ocean. Through the analysis of major elements, trace elements, rare earth elements and LA-ICP-MS zircon U-Pb ages of gabbro, the authors found that the original magma of gabbro was derived between depleted mantle and continental crust, affected by crust assimilation and hybridization. The age of zircon is 514.3±3.7Ma, suggesting that the formation of the ophiolite took place in Middle-Cambrian-Early Ordovician period.