The volcanic rocks in the Triassic Manghuai Formation (MHF) and Xiaodingxi Formation (XDF) are an important component of igneous rock belt in the central-southern Lancangjiang orogeny, and the product of the tectonic evolution of the Lancangjiang Paleotethyan suture. This study reports the petrology, geochemistry and geochronology of the andesitic and rhyolitic interlayers in the thick XDF basalts. Zircon LA-ICP-MS U-Pb dating shows that the XDF volcanic rocks erupted at 230 Ma. Andesite is characterized by high K calc-alkaline, strongly negative Nb, Sr and Ti anomalies, slightly negative Eu anomalies, low Mg#, (La/Yb)N ratios, Cr and Ni contents, which are significantly similar to that of the XDF high Al basalts, indicating the magma of the andesite are the same as that of the basalt and derived from partial melting of metasomatized mantle. The rhyolite in the XDF is strongly peraluminous igneous with negative Ba, Nb, Ta, Sr, P, Eu and Ti anomalies, which are similar to that of the Lincang granite. The Nb/Ta, Th/Ce and Th/U ratios of rhyolites are consistent with that of the continental crust, with εHf(t) values range from -11.6 to +9.6 (the peak εHf(t) values of -6.0~+2.0), which corresponds to crustal Hf model ages (tDM2) of 658~1990 Ma. Most of the ages range from 1100 to 1600 Ma, showing the XDF rhyolitic magma originated mainly from the partial melting of middle/upper crustal rocks, and mingled with a minor volume of mantle-derived melt. Andesites and rhyolites in the thick XDF basalt have similar geochemical characteristics, such as the enrichment in LILE and LREE, strongly negative Nb, Ta and Ti anomalies, and all the samples falling within the active continental-margin arc or syn-collision magma field in tectonic discrimination diagrams. In combination with the lack of the early Triassic strata, unconformable contact between late Triassic molasse formation with the underlying strata, and occurrence of the high-pressure metamorphic belt in the west segment of the Lancangjiang igneous belt, it can be reasonably concluded that the Mesozoic volcanic rocks in the central-southern Lancangjiang orogeny, similar to Lincang granitic batholith, was generated in syn-collision tectonic setting related with the collision between Baoshan and Indochina blocks. The mafic magma derived from metasomatized mantle wedge migrated upward to the crust, and triggered the partial melting of crustal material to form granitic magma. The basaltic magma from lower mafic magmatic chamber and the granitic magma from upper felsic magma chamber erupted intermittently during middle Triassic to form the Mesozoic volcanic belt consisting of the MHF rhyolite with thin layers of andesite and basalt in the low and the XDF basalt with thin layers of andesite and rhyolite on the upper.