Abstract: Junggar Basin is one of key regions of petroleum resources increase in China, and is characterized by oil/gas accumulation of "multisource, multi-stage and multi-type secondary reservoir formation".Through the study for key techniques of superimposed basin, it is put forward that the law of oil/gas enrichment in the basin,and three stages foreland basins developed in the basin evolution history ,giving the different significance in petroleum geologic evolution. Basin superimposed style controls the law of oil/gas enrichment: (1)Oil/gas accumulated at positive position of inheriting and extending plaeo-uplift;(2)Fault cut and reconstructed petroleum accumulation, as a result, the scope of petroleum distribution was enlarged, and the number of oil-bearing beds was increased, which resulted in oil/gas mixed-generating of different sources and made the features of oil/gas distribution complicated;(3)Due to the interrupted change of unconformity, the bottom conglomerate over the unconformity and the weathering crust under the unconformity became the favorable pathways of oil/gas migration;(4) The reservoircap rock combination, controlled by early Cretaceous maximum lake flooding surface, might be important litho-stratum oil/gas reservoirs developed in medium-shallow strata of the basin.