China is rich in graphite mineral resources, and the existing exploration and research results are mostly concentrated in the central and eastern regions. However, the present situation and prospecting potential of graphite mineral resources in Tibet are not clear. With the investment of mineral exploration work, the first large graphite deposit in the Sanjiang area of Tibet was discovered, namely the Qingguo graphite deposit. Its resource is 1.0694 million tons of fixed carbon minerals (indicated and inferred) at average grade of 8.40%. Through detailed field geological survey and borehole geological logging, the basic geological characteristics of the deposit have been clarified. The emplacement age of the ore-bearing pluton was determined by zircon U-Pb geochronology. Combined with the carbon isotopic composition, the genesis and metallogenic age of the deposit were studied. Orebodies in the deposits are hosted in a monzogranite pluton as thick tabular and irregular shape, and graphite is present as ball or irregular rains. These ore-bodies might be formed as the product of recrystallization during the magmatic hydrothermal activity when the coal-bearing strata of the Lower Carboniferous Kagong Formation were captured by monzogranite magma. The U-Pb age of ore-bearing monzogranite yielding (244.7±1.3)Ma indicates its emplacement during Middle Triassic, which represents the magmatic age and metallogenic age. The discovery of many graphite deposits and prospects in Tibet indicate that there is good exploration potential of graphite resources, especially in the Sanjiang area.