Abstract: The Mesozoic volcanic rocks and associated intrusive rocks are widely distributed in the northern and central Gangdese Belt of southern Tibetan Plateau. The petrogenesis and geodynamic setting of these rocks remain hotly debated so far due to the limitation of reliable geochronological and good quality geochemical data. To explore these issues, we report the petrological, zircon LA-ICPMS U-Pb dating, whole-rcok geochemical, and zircon Hf isotopic data for andesites from eastern Bamco, northern Gangdese. One Bamco andesite sample was dated to be 122.1±0.9Ma. The samples are porphyric, with dominant plagioclase, hornblende phenocrysts, together with minor pyroxene, biotite phenocrysts. They have SiO2 of 58.65%~60.16%, total alkalis (K2O+Na2O) of 5.25%~5.52%, K2O of 2.67%~2.81%, TiO2 of 0.61%~0.72%, MgO of 2.78%~3.10%, with Mg numbers of 45~48, and K2O/Na2O>1. The Bamco andesites are enriched in Rb, Th, U, K and Pb, and depleted in Ba, Nb, Ta, P and Ti, indicative of arc-related rocks. The andesite samples have higher εNd(t) values (-9.3~-9.8), higher zircon εHf(t) values (-4.6~-0.3), and lower initial 87Sr/86Sr ratios (0.7102~0.7103) relative to melts derived from mature continental crust in the Gangdese (e.g., Ningzhong Early Jurassic strongly peraluminous granite). The ancient Nd model ages (1.61~1.76Ga) and zircon Hf mantle model ages (795~965Ma) suggest an origin of ancient lithosphere mantle for their generation. Petrological and geochemical data reported here indicate that the Bamco andesites are high-K calc-alkaline, and were emplaced at a transitional setting from continental arc to syn-collisional setting. The Bamco andesites may be the products of magma mixing between ancient lithosphere mantle-derived melts and crust-derived felsic melts resulting from rising asthenosphere material following slab rollback. Such a slab can be correlated with the Bangong-Nujiang Ocean seafloor that has been subducted southward towards beneath the Gangdese Belt.