Objectives: The Ageteng area is located in the western part of the East Kunlun belt. The study of the Late Triassic igneous rocks in this area not only helps to understand of the Indosinian tectonic—magmatic evolution history of the eastern Kunlun orogenic belt, but also can provide constraints for the subduction and the closing time of the Paleo- Tethys Ocean. Methods: Detailed geological survey, LA- ICP- MS zircon U- Pb dating of syenogranite, and whole rock geochemical analysis of igneous rocks in Ageteng area. Results:The zircon U- Pb datings of the rhyolite and granite in the study area are 215.37±0.56 Ma,220.75±0.57 Ma,220.71±0.47 Ma and 220.6±1.4 Ma, which are the product of Late Triassic magmatic activity. The whole- rock geochemical analyses show that the igneous rocks in the Ageteng lie in high K calc- alkaline fields, the aluminium saturation index show the metalumininous and weak peraluminous features, integrated with enrichments of LREE and LILE（Rb, Th, K, et al）, depletions of Nb, Ta, P and Ti（HFSE）and obvious Eu negative anomaly (δEu=0.23~0.76), suggesting plate subduction- related geochemical affinities. Conclusions: Combining achievements of predecessors with this study, it’s believed that igneous rock in Ageteng area generated from an active continental margin arc environment,and it was a product of orogeny during Paleo- Tethys Ocean subduction. The continental crust was not obvious increased in this area,and the Paleo- Tethys Ocean was not completely closed in that period.