The Permian in the Junggar Basin consists of marine-continental transitional facies, lagoon facies, and fluvial facies, possessing widely-distributed source rock and better combination of source rock, reservoir, caprock, trap and preservation conditions. Three large foreland basins formed in western margin, southern margin and northeastern margin of the Junggar Basin as Junggar paleo-plate collided with Siberia plate, Kazakhstan plate and Tarim plate in Middle, Late Carboniferous and Permian, and then three basin-size petroleum systems formed with Fengcheng Formation and lower Wuerhe Formation of the Permian as the main source rock. Based on a static and dynamic aspect analyses of subordinary petroleum system, seven sub-petroleum systems were determined. According to their spatial distribution, four types of petroleum systems were classified; they are synchronous parallel type, synchronous cross type, asynchronous overlap type and asynchronous super-position type. The proper combination formed a favorable oil/gas accumulation belt in the Junggar Basin of Xinjiang.