Abstract: The petrological characteristics of Eocene Granites from the East Sag-uplift of Nyainqenanglha Arc-back study and the whole-rock geochemical analysis on Granitoid rocks showed that the REE patterns of granite presents right decline with Eu as a boundary of left-steep and right-slow style.Granitoid was formed in late stage of collision under tectonic environment of short stress relaxation and stretching.It is generated by the syntexis of the mantle and crustal material during subduction process，and the partial melting of the thickened crust salic.Besides，the deep-sea sediments in upper part of subducted slab also participated in the formation of the magma.Wall rocks consist of the acidic-intermediate volcanic rocks and silty slate stones，sandstone，and limestone.Its structure and growth are in favor of forming the epithermal deposit related porphyry deposit，porphyry-type deposits and skarn deposits.

Key words: East sag-uplift of , Nyainqenanglha arc- back, Eocene, Granide, Metallogenic significance