Granitoid plutons are widespread in Gangou of Central Tianshan orogen. Previous studies of the augen granite and the fine-grained granite from north Gangou revealed that their SHRIMP U-Pb dating ages were 428 Ma and 361-368 Ma, respectively. Comparatively, zircon LA-ICP-MS U-Pb dating of the south granitoid pluton in this study yielded the ²⁰⁶Pb/²³⁸U age of 301±1.0 Ma. Major and trace elements show that the granites belong to high-K calc-alkaline series, and their σ=2.67-3.22. In addition, they are enriched in LREE, Rb, K, Th, La, Zr and Hf, and depleted in Ba, Sr, Nb, Ta, P and Ti. They show a transitional features from I-type to A-type. Compared with the Silurian-Devonian granites, late-Carboniferous granits are characterized by lower I_Sr values (0.704771-0.705451), higher ε_Nd(t) (2.14-2.51) and younger T_DM2 (861-891 Ma), suggesting that more new depleted mantel-derived materials contributed to the generation of the granites during post orogen. It is therefore held that the petrogenesis of the late-Carboniferous granites was related to the underplating of the mantle-derived magmas. This study also provides new evidence for Phanerozoic vertical continental crustal growth in the Central Asian orogenic belt.