|Abstract:The Mangqisu pluton in the central part of the Erbeng Mountain tectonically belong to the South Tianshan Orogenic Belt, and consists mainly of biotite granodiorite unit in the east, biotite granite unit in the west and two-mica granite unit in the central. Our new zircon U-Pb results assign emplacement ages of the eastern, western and central units of 302±4 Ma, 299±3 Ma and 292±2 Ma, respectively. Geochemically, the Mangqisu pluton has SiO2 ranging from 65.34%-72.84%. Samples from eastern and western parts of the pluton show high Al2O3 (14.40%-16.51%), A/CNK (1.00-1.11, the average is 1.05), moderate Na2O+K2O (7.26%-8.52%), and K2O/Na2O ratios ranging from 0.97-1.44 (with an average of 1.21), and are of weakly peraluminous and high-K calc-alkaline series. The central granite unit displays 14.17%-14.92% Al2O3, Na2O+K2O (8.36%-8.80%), and K2O/Na2O ratios (1.61-1.80, the average is 1.72), suggesting that they are of strong peraluminous (A/CNK=1.09-1.14, with an average of 1.12) and shoshonite series. They are enriched in LREE ((La/Yb)N =9.58-44.94, with an average of 28.63 ) and depleted in HREE (LREE/HREE=8.00-22.97, with an average of 16.00), and exhibit negative Eu anomalies, with δEu ranging from 0.67 to 0.81 in the eastern unit, from 0.48 to 0.78 in the western unit and from 0.44 to 0.48 in the central unit. According to primitive mantle-normalized trace element patterns, the studied rocks are enriched in large ion lithophile elements (K, Rb, Ba) and high field-strength elements (Th, U, Hf, Zr, Ce), and depleted in high field-strength element (Nb, Ta, Ti), and have the characteristic of high Sr/Y ratio. In-situ zircon Hf isotopic data of the Mangqisu pluton shows εHf(t) values of the eastern, western and central units ranging from -11.12 to -1.53, -5.31 to -0.35 and -14.43 to -2.51, respectively. And two-stage model age (tDM2) varies from 1.30 Ga to 2.20 Ga. According to Sr-Nd isotope data, εNd(t) value of the eastern ranges from -6.89 to -10.07, the (143Nd/144Nd)i varies from 0.5117 to 0.5119. Combined with regional geological background and previous research datas, we suggest that the Mangqisu pluton can be regarded as syn-collision or early stage of post-collision granitoids and was derived from partial melting of the thickened metamorphic igneous crust, and Experienced different degrees of fractional crystallization.