Fukang sag, a significant hydrocarbon- rich sag in the Junggar basin, exhibits a complex tectono- sedimentary history. This study integrates data from deep drilling wells, well logs, and deep- reflecting seismic profiles from the eastern and surrounding areas of the Fukang sag. By incorporating the tectonic background, fine interpretation, balanced cross- section technique, and sedimentary infill analysis, 3 regional unconformities from the Late Carboniferous to Late Permian were recognized. These unconformities delineate three distinct stages in the tectono- sedimentary evolution of the Fukang sag: ① The extensional fault depression during the early Permian, characterized by the observation of synsedimentary faults at the southern and western edges of the Fukang sag and in the western Junggar basin. The extensional structural stress around the basin weakened during the transmission process from the edge to the interior of the Junggar Basin, with a relatively minor impact of extensional stress on the Fukang sag. The sedimentary facies are mainly fan delta and shallow lake. ② The weak extensional depression in the middle Permian, marked by extensive lake intrusion, occurred in the Junggar basin, leading to an expanded sedimentary range in the middle Permian deposits in the Fukang sag. The stable tectonic environment during the Middle Permian fostered the development of shallow to semi- deep lacustrine sediments characterized by gray and gray- black mud shale deposition. At the end of the middle Permian, transitioning into a compression environment, the Beisantai uplift on the eastern side of the Fukang sag experienced uplift, causing erosion of the Middle Permian strata. Concurrently, the Fukang sag potentially entered the evolutionary stage of a foreland basin. ③ In the Late Permian, the Fukang sag had progressed into the foreland basin evolution stage. This phase was characterized by a compressional tectonic environment, leading to the reversal of pre- existing normal faults from the early stage. This reversal triggered erosion of the middle Permian deposits on the Beisantai uplift. The sedimentary environment in the Fukang sag is characterized by semi- deep and shallow lacustrine facies. The Permian- age characteristics of the Fukang depression profoundly influenced the development and spatial arrangement of hydrocarbon source rocks and reservoirs. The extensive Middle Permian source rocks and the high- quality reservoirs formed during the Late Permian constituted the source- reservoir configuration. The slope zones adjacent to the Monan uplift and Beisantai uplift represent favorable areas for hydrocarbon exploration, while the foreland thrust belt along the southern margin of the depression constitutes an important hydrocarbon region.