Abstract: Located at the northern end of the Yunnan-Myanmar-Malaysia-Thailand microcontinent, the Baoshan block is an important part of multi-island ocean in Paleozoic Tethys of western Yunnan. Bangdong granite intrusion, which is located in western Baoshan block and has LA-ICP-MS zircon U-Pb weighted average age of 228.3±1.7Ma, recorded the process of arc-land collision after the closure of Tethys. The intrusion consists of main orthogranite, with rich silicon and alkali, poor magnesium and calcium as well as rich chromium and nickel, showing evolution tendency of cordierite per-aluminous granite in B-A diagram. On the whole it is enriched in LILE (large ionic lithophile elements) and depleted in HFSE (high field strong elements), thus can be classified as postcollision or post-orogenic granite. Nevertheless, Bangdong granite intrusions, which stay away from Changning-Menglian Tethys main arc-land collision belts, resulted from the mantle lithosphere delamination by micro-block interaction in Yunnan-MyanmarMalaysia-Thailand microcontinent. And it probably resulted from the lithosphere extension at the trailing edge by subduction plate dragging during the closure of Changning-Menglian Tethys.