A set of intermediate and acid volcanic lava, volcanic tuff and volcanic breccia are developed in Yaleman Tousuquan formation in the eastern Tianshan. The magma evolved from neutral to acidic from early to late, and developed explosive facies, effusive facies and subvolcanic facies, with seven eruption rhythmic cycles. According to LA-ICP-MS zircon U-Pb isotopic dating, the rhyolite age of Tousuquan Formation is 406±3.0Ma (MSWD=0.35), and the age is early Devonian. Rock geochemistry shows that the volcanic rocks of Tousuquan formation have the characteristics of medium aluminum (13.20%~18.10%), rich in sodium and poor in potassium (K2O/Na2O=0.10~0.67), and belong to the high differentiation low medium potassium calc alkaline rock series; The total amount of rare earth elements is relatively high (∑ REE=98.7×10-6~214×10-6), LREE is enriched, while hree is depleted (LREE/HREE=3.75~4.58), Eu has no obvious negative anomaly (δEu=0.62～0.92), large ion lithophile elements Rb, K, Ba are significantly enriched, and high field strength elements Nb, Ta and Ti are depleted. The geochemical characteristics show that the volcanic rocks of Tousuquan formation have the characteristics of mantle remelting volcanic rocks, and the crustal materials were assimilated in the process of magma upwelling, and the tectonic environment is the continental margin arc environment under the subduction background.