Objectives: The magmatic activity were well active in western Altay Mountains, the Northern of Xinjiang, but the high precision LA-ICP-MS zircon U-Pb geochronological data of the granitoids is absent. In this work, LAICPMS zircon U-Pb geochronological and geochemical samples of the Qigelatawu intrusive rocks were collected to study the magmatic activity and tectonic evolution information of the Altay orogenic belt. Methods: Based on LA-ICP-MS zircon U-Pb isotope dating, defining the formation age of the Qigelatawu intrusion, and using geochemical data of the intrusive rocks to distinguish the magmatic genesis and tectonic environment of the Altay orogenic belt. Results: The LA-ICP-MS zircon U-Pb age (206Pb/238U weighted average age) of the Qigelatawu intrusive rocks is 425.1±4.4 Ma, revealed that the intrusive rocks formed in the Middle Silurian. The SiO2 content ranges from 64.07% to 73.77%, Al2O3 content range from 12.4% to 15.71% and A/CNK ranges between 0.88~1.16, ALK ranges between 5.85%~7.93% and σ from 1.62 to 2.24, with wearly peraluminous, highK calcalkaline series rocks. The content of REE ranges between 166.28×10-6~197.22×10-6, light—heavy REEs fractionation strong, Eu negative anomalies(δEu = 0.47~0.63). The geochemical characteristics of the pluton are that trace elements are enriched in Rb, Th, U (LILE) and La, Ce, Sm, etc., poored in Nb, Zr (HFSE) and Sr, P, Ti, etc., low in Sr and high in Yb ( Sr ranges between 93.7×10-6~211×10-6，Yb ranges between 2.1×10-6~3.9×10-6). This study demonstrated that the Qigelatawu intrusion has the characteristics of subduction environment and shows the characteristics of postcollision granites. Conclusions: Research shows that ancient Asian Ocean subducted north from the Ordovician and continued until the late Middle Paleozoic. The Qigelatawu intrusive rocks , which formed at the end of Early Paleozoic, its complex causes may be related to the ridge subduction in the ancient Asian Ocean.