Abstract: The study of evolution of paleostructural framework and the analysis in combination with the thermal evolution history of hydrocarbon source rock and petroleum migration and accumulation history were made, by which the Cambrian petroleum system was firstly clssified. Based on known resen oir-forming processes and trap- formed period, the critical event and critical timing for shaping a petroleum system were determined. The petroleum system assumes complex combinations vertically and horizontally compared with the others. This paper suggested that the most favorable zones for oil gas exploration would be Qunkuqiake and Mazatag torsional and folded belts, and the major prospecting objective might be Haimixi anticline in Haimitag structural belt, the secondary one be Jiedong fault-nose within Cambrian “salt base" trap in west end of Bachu uplift.

Key words: Tarim basin, Southwest, Cambrian, Oil and gas migration, Oil and gas accumulation, (Petroleum systerm), Exploration policy