Yining sag has good oil and gas exploration prospect and complicated tectonic conditions due to the orogeny of the North，Central and South Tianshan，so it is important to carry out research on tectonic style and its relation with oil and gas in the region. Based on comprehensive analysis，thrust faults developed in Yining sag in NW-NWW，formed in the Hercynian period，mostly activated continuously during the Indo-Chinese and Yanshan epoch and became silent in the Himalayan period. According to the characteristics of fault development and its control degree on deposition and structure，faults in the study area can be divided into three types：deep fault controlling basin，large fault controlling zone and secondary fault controlling structure. And they are combined with fold to form the fault-folded structures which include ramp and back thrust，imbricate structure，Y-type structure，flower structure and so on. According to tectonic style and structure deformation level，Yining sag from north to south can be divided into north rim strong deformation zone，Huocheng-Quluhai weak deformation zone，Cha County-Well Y2 medium deformation zone and south strong deformation zone. Yining sag experienced four evolutionary stages since Mesozoic：the large-scale fault-depression basin formed in the Indo-Chinese epoch，the formation and development of foreland basin in early-middle Yanshan epoch，the uplifting of basin as whole and imbalanced basin reformation in the late Yanshanian period，the imbalanced development of Paleogene-Neogene sediments in the Himalayan period. In the process of tectonic evolution，three sets of main hydrocarbon source rocks deposited and remained in the area，including the middle Permian Tamuqisayi Formation，the upper Triassic Baijiantan Formation and the Lower Jurassic Badaowan Formation，in which large-scale hydrocarbon expulsion happened respectively in the Indo-Chinese and Yanshan epoch and the early-late Yanshanian period. The fault fold structure zone，formed in the IndoChinese epoch，is the main pointing area for oil and gas migration and accumulation. More attention should be paid to the fault-folded structure of Y-type structure and flower structure in the Cha County-Well N4 for oil and gas exploration.