Abstract: The East Kunlun Orogenic Belt is an important part of the Paleo-Tethys domain, and there are still disagreements regarding the closure time limit of the Paleo-Tethys Ocean in this area. Volcanic rock interlayers in the Hongshuichuan Formation in the Gouli area of the eastern segment of this region were selected for zircon U-Pb isotopic age and petrogeochemical studies. The results show that this suite of volcanic rocks is composed of basaltic andesite, dacite, and rhyolite. The selected zircons in the dacite and rhyolite samples all exhibit magmatic rhythmic zoning, and most of them have a high Th/U ratio, indicating that they are of magmatic origin. The LA-ICP-MS zircon U-Pb ages are (250±2.1) Ma (MSWD=4.9) and (248±4.5) Ma (MSWD=1.2), representing that the volcanic rocks were formed during the Olenekian period of the Early Triassic. Petrogeochemical analysis shows that this suite of volcanic rock interlayers belongs to the calc-alkaline series, showing the characteristics of enrichment in large ion lithophile elements (LILE) such as Rb, Ba, Th, and U, depletion in high field strength elements (HFSE) such as Nb, Ta, P, and Ti, and no obvious anomalies in Zr and Hf, exhibiting the characteristics of arc magmatic rocks related to the subduction zone. The basaltic andesite is a magma from the mantle source area metasomatized by subduction fluids, formed through later crystallization differentiation and crustal material contamination; the dacite and rhyolite have a homologous evolutionary relationship and are products of crustal melting induced by the upwelling of mantle-derived magma, formed in the environment of northward subduction of the Paleo-Tethys Ocean. The study on the age and sedimentary environment of the volcanic rock interlayers in the Hongshuichuan Formation limits that the closure time of the Paleo-Tethys Ocean in the East Kunlun area is not earlier than 248 Ma.