Located at southwestern convergence belt of Yangtze and Cathaysia Massifs near Xialuoxing village, Rongxian county, southeastern Guangxi Zhuang Autonomous Region, the Early Triassic volcanic vent (pipe) is highly significant in studying the Indosinian regional tectonic evolution of South China. The vent consists of a suite of cryptoexplosion breccia, rhyolite, trachyandesite porphyrite, felsites porphyry, with columnar joints, and shows characteristics of super-hypabyssal intrusion and effusive facies. The LA-ICP-MS zircon U-Pb dating of rhyolite from the vent gives a weighted average age of (249. 9 ± 1. 6) Ma (MSWD = 1. 9), which represents the eruption age of volcanic rocks and suggests the production of Early Triassic magmatism. Geochemically, the intrusive rocks belong to shoshonite to high potassium-calc alkaline series, with low TiO2 content, high K2O / Na2O ratio, obvious depletion of high field strength elements such as Ta，Nb，P，Ti, and are typical of the arc volcanic rocks. Zircons of these rocks have εHf(t) values of -14. 50 to -6. 61, with corresponding single-stage Hf mode age (TDM) 1. 17 ~ 1. 49 Ga and two-stage model age (T2DM) ranged from 1. 70 to 2.20 Ga. Comprehensive data analysis on the geochemistry, Hf isotopic characteristics of zircon and regional geology suggest that the Xialuoxing volcanic rocks were formed by melting of the Paleoproterozoic meta-sedimentary rocks in an extensional tectonic setting. Heat input associated with the upwelling of asthenosphere mantle might have played an important role in crustal melting and crystallization of the granitoids. Geodynamically, the formation of the Xialuoxing volcanic rocks were related to the subduction of the Paleo-Pacific plate.