Abstract: The Tasite pluton is located in the Sawuer Mountain of West Junggar, Jimunai County, Xinjiang.The pluton consists of granodiorite, monzonite granite, etc. According to U-Pb age analysis, the formation age of the granodiorite from the Tasite pluton is (332±1.9)Ma(the middle stage of Early Carboniferous).The geochemical studies indicate that the SiO₂ contents vary from 64.03% to 66.44%, Na₂O/K₂O ratios change from 1.887 8 to 2.488 5, A/CNK ratios range from 1.7667 to 1.9204, which belongs to the I type granite. This pluton is enriched in LILE, such as Rb and K, and depleted in HFSE, such as Nb and Ti. The pluton has low ΣREE contents (54.68×10^-6~57.56×10^-6) and no Eu anomalies, with δEu values of 1.03~1.09and the (La/Sm)Nratiosvarying from 3.173 to 3.54. All of the geochemical features above show that the Sawuer Mountain in the middle stage of Early Carboniferous or the West Junggar are in post-collisional environment. The confirmation of post-collisional I type granites in the middle stage of Early Carboniferous provides new tectonic evolution evidence for the West Junggar region.