The Nalati quartz monzonite located at Awulale mountain, northern margin of the Ili tiny Plate, intruded in the Upper Carboniferous Yishenjilike Formation, The weighted average age dated by LA-ICP-MS U-Pb method of zircons is 307.0±2.5 Ma, representing its crystalline and intrusive age. Petrogeochemical analyses suggest the quartz monzonite belongs to calcalkaline—alkaline metaluminous granite series, which is characterized by high silica, aluminum and alkaline, σ is 3.09~3.94, A/CNK is 0.75~0.91;the rocks have relatively high total of Rara Earth Elements (REE) content with LREE riched patterns \[(La/Yb)N=2.86~6.14\] of chondrite normalized, LREE are differentiated intenser than HREE, Eu show obviously negative anomaies(δEu=0.46~1.02，average=0.69); The rocks enriched in large ion lithophile elements (LILE) Rb, Th and K, while strongly depleted in high field strength elements (HFSE) Nb,Ta, Ti and P; these show that the Nalati quartz monzonite has the characteristics of A2type granite.The high Th values (8.68~14.62μg/g) and low Nb/Ta ratios (12.23~29.90，average18.13) imply that the mainl source of magma was continental crust, but the magma experienced a significant contamination by mantle. In the tectonic setting discrimination diagrams (Nb—Y—Ce, Y/Nb—Ce/Nb, Rb—(Nb+Y) et al.), the most data project into the area of postorogenic or late orogenic granite. Writers reach a consensus that the rock was the product formed during the period synorogen transformed to postorogen or late orogen, it was formed by postorogenic or late orogenic magmatism. Combining with regional geological setting, this study suggests that the Ili tiny Plate and Junggar tiny Plate had collided before the time of 307.0±2.5 Ma, the northern Tianshan oceanic basin had closed before Late Carboniferous.These new data provide new constrains for tectonic evolution of the Western Tianshan Mountains.