Nadun deposit is located in the southwest of the Duolong orecluster district in the Bangong CoNujiang River metallogenic belt of Tibet, which has huge potential of mineralization. But its research and exploration degree is very low and only one Aubearing body has been delineated. Therefore, this deposit is of great outlook for prospecting. This study carried out research on facieology and mineragraphy, fluid inclusions and geochemical characteristics of the Nadun deposit. Principal altered minerals in the Nadun deposit include kaoline, sericite, epidote, calcite and dolomite, etc, in company with typical metal mineral assemblage, such as electrum, cinnabar, galena and sphalerite. Homogenization temperatures of fluid inclusions in phenocrysts and cements distribute mainly between 222℃ and 360℃. The fluid inclusions are dominated by H2O, with minor CO2. Salinities of fluid inclusions in phenocrysts can be divided into two groups: high values （1835%~267%NaCleqv.）and low values （018%~1285%NaCleqv.）. While the salinity of fluid inclusions in cements is low and ranges from 16% to 125%NaCleqv. 〖JP2〗These results suggest that fluid inclusions formed in the environment of mediumlow temperature, low salinity and oxidization and oreforming fluids of the Nadun deposit were distinctly affected by atmospheric precipitation. The SiO2 content of granodiorite porphyry is in the range of 559~6567% (averaging 6052%) and the Na2O+K2O values of samples are in the range of 354~5563 percent (averaging 483%), indicating that rocks belong to peraluminous rocks of highpotassium calcalkaline series to shoshonite series. A/CNK values are in the range of 163~293, and the average is 26, reflecting that protolith is peraluminous rocks. Granodiorite porphyry has a total REEs of 2909×10 -6~9873×10-6, with slightly negative Eu anomalies（δEu=07~112）and without Ce anomaly（δCe=084~099）. The rocks are characterized by enrichment of large ion lithophile elements （Rb and K）and depletion of high field strength elements （Nb, Ta, P and Ti），suggesting typical features of island arc volcanics.〖JP〗 Ratios of Co/Ni in veined pyrites range from 005 to 8523 with an average of 4219, and this indicates that the veined pyrites are of hydrothermal genesis. Paragenetic relationship between veined pyrites and quartz breccia vein suggests that they are the product of late hydrothermal minerallzation. δ34S values of pyrites are in the range of -045~007 percent, and the average is -0195 percent; δ34S values of chalcopyrites are in the range of -07~-033 percent, and the average is -0543 percent; relatively low δ34S values with part being negative show that sulfurs in the deposits were affected by reducing sulfur. Main orebearing rock of the Nadun deposit is granodiorite porphyry in which characteristic minerals (electrum and cinnabar) have been found in the deposit. Fluid inclusions are characterized by mediumhigh temperature fluids of porphyry copper (gold) deposits. Therefore, the genetic type of the deposit belongs to porphyry copper (gold) deposit superimposed by lowsulfur epithermal deposit. The factor analysis shows that the earliest diagenesis resulted in the formation of intermediatefelsic rock bodies. The main mineralization of the deposit should be hydrothermal coppergold mineralization, followed by leadzinc mineralization, magnetitization and potassic alteration, with involvement of carbonatic fluid in the late stage of mineralization.