As a important partion of the ancient Yili Rift, the western Awulale Mountain possess typical bimodal volcanic rocks(basalts-rhyolite) in the Lower Permian Series. These rocks are generally characterized with higher Na2O and Al2O3 contents, lower TiO2 content and alkali-rich. The basalts are enriched with large-ion-lithophile elements(LILE)such as Ba, K, P and light rare earth elements(LREE), depleted of high-field-strength elements (HFSE)such as Th, U, Ta and Nb. Comparatively, the other rocks are enriched with Rb, K , LREE and Th, U, Zr and Hf, depleted of Ta, Nb, Sr and Ti. The basaltic magma is derived from weak depleted mantle and possibly contaminted by lower crust. In contrast, the rhyolites are production resulted from partial melting of crust. The petrogenesis of bimodal volcanic rocks is associatied with the underplating of the basaltic magma. Mixing and materials exchanging happened between acidic magma generated from melting of lower crust and the basaltic magma. The Yili Rift is generated under extensional stresses in response to the post-orogenic stage. The rift system in western Awulale Mountain evolves to its maturity and rapidly weaken at end-stage of Early Permian because the tectonic setting is changed from extension to compression. The late Carboniferous period-early Permian period rift evolution in western Awulale Mountain is accordant with the tectonic evolution of Tianshan orogen in late Paleozoic.