The West Junggar area of the Central Asian Orogenic Belt, known for its complex tectonic movements, extensive magmatic activities and remarkable crustal growth, was formed 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 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. High- precision zircon U- Pb dating indicates that the Jietebutiao pluton was formed between 287~250 Ma pointing to multi- stage magmatic activity events during the Early Permian- Early Triassic. The Early- Triassic (2504 Ma) 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 activity. Jietebutiao plutons are characterized by high silica (SiO2=6704%~7701%), high- K calc- alkaline (K2O=345%~463%, Na2O=362%~418%, CaO=045%~0305%), low magnesium (MgO=016%~151%), low iron (FeOT=099%~440%), quasi aluminum- weak peraluminum (Al2O3=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 pattern 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 characteristics similar to the 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 the A- type granite, belongs to the highly fractionated I- type granite. The monzonitic granite and granodiorite, characterized by high crystallization temperature, belong to the magmatic mixed I- type granite. Compared with the existing research results, we are convinced that the Jietebutiao pluton evolved during the stage of the intracontinental tectonic activity under the post- orogenic extensional environment with high temperature, low pressure and crustal thinning during the Early Permian- Early Triassic.