Abstract: Gangdese tectonic belt is a major one in Cuoqin basin, in which the magmatic action was very strong in the periord of Mesozoic and Cenozoic era. This study shows it belongs to a complete intrusive rocks belt from intermediate diorite to acid granite. The study on the rock types, petrochemical characteristics and petogeochemical characteristics of the intrusive rocks reveals that its rock types are dominated by granodiorite, adamellite and quartz monzonite which belong to calc-alkalic rock series and have the characteristics of "Ⅰ" granite.They are the products of lower crustal matter melting and upt ruding caused by the northward subduction of the New-Tethyan crust along the Yarlung Fracture in the late Yanshanian period.