Abstract: The source rocks from the Quse Formation in southern Qiangtang Basin on the Qinghai-Xizang Plateau consist of black oil shales, dark grey argillutites and dark grey marls, with a total thickness of about 215.8 m. The results of assessment of the source rocks indicate that the organic matter abundances are higher, including 9.23% for black oil shales, 2.21% for dark grey argillutites and 4.33% for dark grey marls, respectively. The organic matter types are classified into the type II for the argillutites, and dominantly the type II and subordinately the type III for the oil shales and marls. The pale brown colour for the kerogens and higher Tmax values (430℃-470℃) for the collected samples suggest the source rocks from the Quse Formation have reached up to the mature stage.