The temporal and spatial distribution characteristics of Permian—Triassic intermediate acidic magmatic rocks in the Lancang tectonic belt, as well as the PaleoTethys tectonic evolution information it contains, remain to be further elucidated. This study conducts geochronological, petrological, and geochemical research on Permian—Triassic intermediate acidic magmatic rocks in the middle segment of the Lancang tectonic belt, yielding four granitoid intrusion ages of 284.1±4.1 Ma, 257.1±5.3 Ma, 249.8±7.1 Ma, and 230.4±2.6 Ma, respectively, which represent the northern extension of the Lincang Granite Batholith. The Permian granitoids in the study area are enriched in large ion lithophile elements (e.g., Rb, K, Th, U) and light rare earth elements (e.g., La, Ce, Nd), while exhibiting depletion in Ba, Sr, P, high field strength elements (e.g., Nb, Ti), and heavy rare earth elements, significantly similar to typical subduction- related arc volcanic rocks. The magma source of the Late Permian diorite may have originated from mantle wedge that were metasomatized by slab- derived aqueous fluids, whereas the magma source of the Triassic granites most likely originated from partial melting of the upper crust with limited addition of mantle components. The early Triassic monzogranite exhibits geochemical characteristics of enrichment in SiO2 and K2O, and depletion in Al2O3, Sr, Ba, and Eu, with REE distribution showing a distinct negative Eu anomaly, indicative of A- type granite affinity. It formed within a tectonic setting transitional from syn- collisional to intraplate environments. Considering the geochemical features of contemporaneous volcanic rocks in the southern segment of the Lancang tectonic belt, it is proposed that the Lancang tectonic belt underwent a structural transition from subduction to collision during the Early Triassic, subsequently entering a rapid orogenic collapse stage. By integrating the trend of decreasing ages from east to west in the Permian—Triassic composite granite belt of the Lancang tectonic belt, along with the north—south zonation characteristics and regional geological data, this study suggests that the temporal and spatial distribution pattern of Permian—Triassic intermediate acidic magmatic rocks in the Lancang tectonic belt and its magmatic evolution may be related to the deep dynamic mechanisms associated with the eastward subduction of the PaleoTethys slab followed by slab rollback.