Abstract: A series of alkali and meta-alkali granitic intrusives occur along Zahebar-Sarterik-Tasgark-Almat on the south bank of Ulungur River and are controlled by Ulungur deep fault in the northwest part of Eastern Junger, Xinjiang, which form a distinctive alkali granite belt in the area. This belt, in association with Ulungur ophiolite belt nearby, has important significance in tectonics of the area. Evidences from geology, mineralogy, petrology and geochemistry show that these granites in the Ulungur alkali granite belt fall into Type A in granitoid classification. However, they contain high contents of Fe2O3, MnO and have higher ratio of Na2O/K2O, in comparison with typical A-type granitoids known at home and abroad. On the basis of comp0rehensive study and previous works on the Ulungur alkali granites, the authors suggest a composite model of “mantle material transport + partial melting of dehydrated sial source +granitic magma differentiation + tensional tectonics” to explain well the petrogenesis of A-type granites in this area. Geochemical plots, together with the analysis on evolution of the regional tectonics, show that the Ulungur alkali granites intruded during the post collision-orogeny tensional tectonic significance because not only they mark the termination of Easter Junger orogeny, but also their spatial distribution, together with the Kalimaili alkali granites in the south, demonstrates the presence of grand suture between the Siberia plate and the Khazakstan plate. It again proves that the study of granitoids plays an important role on geotectonics in certain area.