Amduo trachyte is located at the middle segment of the Bangonghu-Nujiang Suture, and adjacent to the northern side of the Amduo ophiolites. The outcrop area of the trachite is about 30 km2, with accumulated thickness about 1 500 m. The features of trachyte show that it is continental volcanic rock with a relatively complete volcanic apparatus. The rock association which falls into shoshonite series includes latite, quartz latite, trachyte and some volcaniclastic rocks, but the trachyte is the major type. The characteristics of the petrochemistry, geochemistry and isotope-tracer measurement together suggest that the trachyte has relatively high pressure forming condition and belongs to potassic rocks fromed during post-orogenic process triggered by continental collision.