The Awulale tectonic magmatic belt is an important Fe-Cu metallogenic zone in western Tianshan Mountains, with especially lots of Cu deposits and ore spots discovered in the western Awulale. Nevertheless, the Permian geodynamic background and the metallogenic environments in this area remain unclear. Middle-high potassium calc-alkaline trachyandensite newly discovered at the bottom of Wulang Formation section of volcanic rocks in Qunjisayi area was studied in this paper. La-ICP-MS zircon U-Pb dating of trachyandesite yielded a ²⁰⁶Pb/²³⁸U weighted average age of 300 ±11Ma. Trachyandesites in Qunjisayi area are geochemically characterized by enrichment of light rare earth elements (LREE) and large-ion lithophile elements (LILE, such as Rb, Ba, and K) and flat distribution of heavy rare earth elements (HREE), together with strong negative Nb, Ta, Ti anomalies. The rocks have whole-rock εNd(t) values of +4.5 to +4.9, and Nd isotopic model ages (t_DM) of 808~765 Ma, indicating that the rocks originated from a fluid metasomatic mantle magma source. Similar to features of a large amount of granite exposed in the northern part of the central Asian orogenic belt, the t_DM values are relatively young, and the acidic rocks in the study area have similar isotope geochemical characteristics. The magma probably came from the partial melting of the new basaltic lower crust. The West Tianshan Mountains entered the past-collision evolution stage in the Early Permian, and the formation of the high potassium calc-alkaline trachyandesite magma with arc features might have been related to the partial melting process of the new basaltic lower crust during the upwelling of asthenosphere material and energy that resulted from the break-off of the oceanic lithosphere plate tail that postdated the closure of the North Tianshan Ocean, which was the mark of the final stage of the evolution of the orogenic process. Meanwhile, the tectonic system correspondingly changed from the subduction extrusion background to the extensional tension background.