Objectives: The Qiangtang Basin is the largest and most potential petroliferous basins in eastern Tethys, China. It contains a series of marine argillaceous source rocks, in which the Upper Triassic Tumengela Formation, Lower—Middle Jurassic Quse and Sewa Formations and Upper Jurassic Amdo Formation have great potential for hydrocarbon generating.Methods: Based on the previous data, we evaluated the hydrocarbon- bearing potential of the three Mesozoic argillaceous source rocks in the South Qiangtang Depression through a comprehensive organic geochemical analysis, predicted the favorable hydrocarbon generation area and discussed the main factors in controlling high- quality source rocks. Results: The organic matter of the Tumengela Formation is mainly type II and has medium to low organic abundance and relative high maturity, overall belong to the medium- to good- grade source rock. And its favorable hydrocarbon generation areas are located in the Duopuleinai—Chalangla area of Shuanghu and Dazhuoma—Tumen area of Amdo. The Quse and Sewa Formations is poor source rock with mainly II1- type organic matter, low organic material abundance and highly to past maturity, and its favorable source rock kitchens contain the Angdaercuo area in the West of the South Qiangtang Depression, Zhaqu area in the Central and Damaer area in the East. In addition, a comparatively restricted favorable hydrocarbon generation area is existed in the Bilong Co area, Shuanghu. The Amdo Formation is generally classified as Type II1 and in the mature thermal evolution phase and has high abundance of organic matter, forming a set of superior source rock with a restricted favorable hydrocarbon- generating area in the 114 Station of Amdo.Conclusions: Sedimentary environment is the main factor in controlling the deposition of superior argillaceous source rocks in the South Qiangtang Depression. Both of the warm humid climate and relative higher accumulation rate provide a favorable condition for source rock deposition of the Tumengela Formation. The Quse—Sewa Formations deposited in the epicontinental—shelf settings are poor source rocks, whereas those deposited in a barrier—lagoon environment are very good source rocks. Sluggish and reducing environment in trench and stable organic matter supply from shallow water facilitate the deposition of organic carbon- rich sediments in the Amdo Formation.