Abstract: Integrating with heavy mineral analysis, the study presents that during E,2 in the southwestern Qaidam basin there exist several sedimentary provenances such as Qigequan- Ahadi, Alaer, Qimantage and Dongchaishan, with heavy mineral assembl ages of eight sub-areas. These provenances are of some diferences in the sedimentary characteristics and facies types: Qigequan-Ahadi is doninated by short-distance and gravity flow deposits; Alaer dominated by medium-fine and fluvial-lacustrine deposits， and Qimantage and Dongchaishan dominated by fine lacustrine deposits or sedimentation. It is predicted that the provenance in the middle part of study area is generally premium in reservoir quality, the north part is secondary, and the southwestern part is poor.

Key words: Qaidam basin, southwest, heavy mineral, provenance, reservoir, reservoir quality