The Kongwusayi granitic pluton is located in the south slope and east side of the Alataw Mountain, West Tianshan of Xinjiang. The pluton is composed mainly of alkali- feldspar granite, coarse grained K- feldspar granite and fine grained K- feldspar granite. The weighted average U- Pb age of zircons in the alkali- feldspar granite and the fine grained K- feldspar granite are 293.1±3.6 Ma and 293±3.7 Ma, respectively. The three types of granites belong to aluminum- weakly peraluminous and high potassium calcium alkaline series. Eu negative anomalies increase quickly from the alkali feldspar granite to the coarse grained K- feldspar granite and the fine grained K- feldspar granite, and depletion degree of Ba, Sr, P, Ti and the enrichment degree of Rb, Th, U are gradually increasing, indicating a tendency of crystallization differentiation between the three magma types. These granites are enriched in Ga with high 104Ga/Al (2.6~3.5),Fe* (0.88~0.97) and TiO2/MgO (0.51~1.25), suggesting that they are characteristic of A- type granites. A- type granites in the study area are characterzied by the high saturation temperature of zircons (853.86~931.56℃) and low Ce(Ⅳ)/Ce(Ⅲ) (1.9~77), implying that the A- type granites were formed in higher temperature and lower oxygen fugacity conditions. The Kongwusayi granites have higher Y content (43.3×10-6~106×10-6), higher εNd(t) (+3.0~+5.2) and lower (87Sr/86Sr) i (0.7027~0.7069), suggesting that the Kongwusayi A- type granites may formed by the partial melting of the basaltic crust. By comparing with the carboniferous basalt in West Tianshan, the Kongwusayi A- type granites display lower εNd(t) and higher (87Sr/86Sr)i, indicating the magma source of the kongwusayi A- type granites may include the ancient crustal materials.