The Baleigong granitic pluton, located in the western part of South Ti anshan Accretionary Orogenic Belt, Xinjiang, is composed mainly of biotite monzogranite. LA-ICP-MS zircon U-Pb analysis of two samples yielded crystallization ages of 291±3 Ma and 283±3 Ma. The pluton possesses high SiO₂(65.88%~72.99%), K₂O(4.23%~6.86%) and total alkali(K₂O+Na₂O=7.45%~9.96%) values. With respect to trace(including REE) elements, the samples are characterized by strong troughs in Ba, Nb-Ta, Sr, P and Ti, slight to moderate enrichment of LREEs and negative Eu anomalies(δEu=0.27~0.60). These features suggest that the Baleigong pluton is of A-type in genesis. Zircons from the pluton show εHf(t) values from-4.3 to +1.7 and corresponding two-stage Hf model ages from 1.20 Ga to 1.58 Ga. Zircon Hf isotope and whole-rock geochemistry implies that the parental magma was derived from the partial melting of Mesoproterozoic amphibolite-facies mafic lower crust rocks at high temperature and low pressure. The country rocks of the pluton belong to parts of ophiolitic mélange that represent the remnant of Paleo-South Tianshan Ocean. The Baleigong pluton, which was undeformed and intruded into the unit of ophiolite mélange, can be regarded as a "stitching pluton". Therefore, the final closure of the oceanic basin and the collision of continental blocks is expected to have occurred before the emplacement of the pluton(before Early Permian). On a regional scale, zircons from Early Permian granitoids and acid volcanic lavas predominately show Late Paleoproterozoic to Late Mesoproterozoic two-stage Hf model ages, implying that sources for those felsic magmas were dominantly composed of ancient crustal rocks with negligible juvenile materials.