Abstract: Oil and gas resources are abundant in the southern margin of Junggar Basin with multi-layered geological structures and complicated and variable structural styles, which features the most complex petroleum geological conditions and the most tortuous exploration history. In recent years, with the improvement of the geological theories, the progress of seismic and drilling technologies, and the shift of exploration strategies for hydrocarbon exploration of ultra-deep clastic rocks in the foreland at the southern margin of Junggar Basin, a large gas area of ultra-deep clastic rocks has been discovered in the middle section of the southern margin of Junggar Basin. Exploration practices and researches show as follows. (1)Five sets of source rocks, i.e., the Permian, Triassic, Jurassic, Cretaceous, and Paleogene, are developed in the southern margin of Junggar Basin. Among them, the Jurassic and Permian as the main source rocks have entered the stage of large-scale gas generation and possess the material basis for the formation of large and medium-sized gas fields. (2)The lower assemblage has developed multiple sets of large-scale reservoirs such as the Cretaceous Qingshuihe Formation, and the Jurassic Kalazha Formation, Toutunhe Formation, Sangonghe Formation, and Badaowan Formation. The superimposition of pore-type and multi-scale fracture-type reservoirs forms a large-span fracture body, providing reservoir conditions for high natural gas production. (3)The regional thick quilt-like ultra-high pressure mudstone caprock of the Cretaceous Tugulu Group has good preservation conditions, which is the key to natural gas accumulation. (4)The large-scale anticlinal structural trap group distributed in rows has developed in a belt-like pattern. According to the superposition pattern of structures, the southern margin of Junggar Basin can be divided into three rows of tectonic belts (thrust belt, detachment fold belt and frontal slope belt), including seven structural belts (buried structural belt, Dongwan structural belt, Wuchang transfer belt, Huomatu structural belt, Du’an structural belt, Hutubi structural belt and Fangcaohu structural belt). It is clear that Dongwan structural belt, Hutubi structural belt, Wuchang transfer belt and buried structural belts are most favorable anticlines for natural gas preservation. During exploration of the southern margin of Junggar Basin, a sequence of techniques such as high-precision seismic acquisition, full-depth modeling and migration imaging, and fine description of traps for the "double complex" structures (complex surface and subsurface structures)in the ultra-deep piedmont has been established, as well as the key supporting technologies involving fine evaluation of ultra-deep, ultra-high pressure and ultra-high temperature clastic rock reservoirs, optimal fast drilling and completion, and safety testing. The breakthrough of natural gas exploration in the middle section of the southern margin of Junggar Basin has effectively promoted the exploration and development of natural gas in ultra-deep clastic rocks, thus enriching the petroleum geological theories of continental ultra-deep clastic rocks.