|Abstract:The West Junggar of the Central Asian Orogenic Belt, known as complex tectonic movements, extensive magmatic activities and remarkable crustal growth, was in a critical period of ocean-continent transition in the Late Paleozoic. Jietebutiao pluton, located in the West Junggar area, Tianshan Orogenic Belt and Junggar Basin, is mainly composed of alkali feldspar granite, monzogranite and granodiorite in the southwest of the West Junggar. The alkali feldspar granite, whose mineral composition consists of potassium feldspar (60%~65%), plagioclase (10%~15%), quartz (23%~25%) and few dark minerals, has no mafic microgranular enclaves. The monzonitic granite and granodiorite, whose mineral composition respectively consists of potassium feldspar (30%~40% and ~16%), plagioclase (30%~40% and ~50%), quartz (20%~25% and ~18%) and a small amount of dark minerals, has visible mafic microgranular enclaves .Jietebutiao pluton were formed during 287~250 Ma by high-precision zircon U-Pb dating, which indicates the multi-stage magmatic activity events during the Early Permian–Early Triassic. The Early-Triassic (250.4Ma) monzogranite is the youngest intrusive magmatic rock that has been found in the West Junggar so far and its intrusion means the end of Late Paleozoic magmatic intrusion activitie. Jietebutiao plutons are characterized by high silica (SiO2 = 67.04%~77.01%), high-K Calc-alkaline (K2O = 3.45%~4.63%, Na2O = 3.62%~4.18%, CaO = 0.45%~0.3.05%), poor magnesium (MgO = 0.16%~1.51%), low iron (FeOT = 0.99%~4.40%), quasi aluminum–weak peraluminum (Al2O3 = 12.60%~15.01%). Trace elements of the Jietebutiao pluton have obvious right-leaning seagull type characteristics with distinct negative Eu anomalies in the chondrite-normalized Rare Earth Elements distribution patterns diagram, enriched in Light Rare Earth Elements and Rb, Th, K, depleted in Heavy Rare Earth Elements and Eu, Ba, Nb, Sr, P and Ti. The pluton shows the similar characteristics as I-type granite in terms of major and trace element, but there are also some differences between alkali feldspar granite and other granites. The alkali feldspar granite, characterized by low crystallization temperature compared with A-type granite, belongs to highly fractionated I-type granite. The monzonitic granite and granodiorite, characterized by high crystallization temperature, belong to Magmatic mixed I-type granite. Compared with the existing research results, we convinced that Jietebutiao pluton evolved into the stage of the intracontinental tectonic activity under the post-orogenic extensional environment with high temperature, low pressure and crust thinning during the Early Permian–Early Triassic.