Located in northwestern Baingoin County of Tibet, Duoba area is near the middle of Bangong Co-Nujiang River metallogenic belt with the distribution of a large number of skarn iron-copper polymetallic deposits (mineralization spots) characterized by good prospecting potential. Due to high elevations, traffic inconvenience and less mining, only a small amount of work has been carried out. This research is based on the systematic field geological survey, indoor petrographic and ore microscopic studies, zircon LA-ICP-MS U-Pb dating and analysis of major and trace elements. The authors chose Sousha skarn mineralization spot and Zai'a skarn iron polymetallic deposit to conduct researches on the relationship between the petrogenesis and the mineralization. There are mainly fine grained porphyritic granodiorites in Sousha area and fine grained granodiorites in Zai'a. Zircon's LA-ICP-MS dating indicates that the age of the fine grained porphyritic granodiorite is 77.37±0.55 Ma, whereas that of the fine grained granodiorite is 79.78±0.99 Ma, suggesting products of late Cretaceous magmatism. Their A/CNK values change between 0.78 and 1.29, and A/NK values change in the range of 0.88～1.51. The rocks belong to weakly peraluminous. They are enriched in big ion incompatible elements Rb, Th, U and K, and depleted in Nb, identical overall with the same period granite in Bangong Co-Nujiang River metallogenic belt. ∑ REE range from 199.82×10^-6 to 274.64×10^-6, LREE/HREE= 3.552～7.199, δEu=0.20～0.82, with medium negative Eu anomalies. These data indicate that the separation of plagioclase crystallization might have occurred in magmatic evolution processes. The ore-forming processes of Sousha and Zai'a rock bodies might have had something to do with the southward subduction of the Bangong Co-Nujiang Ocean Basin and acted as the products of magmatic activity after closing. With favorable iron and bismuth polymetallic ore-forming geological and geochemical conditions, this area deserves more attention in further prospecting and evaluation work.