Eight gas-enriched units, including Jinbian, Sulige, Wushenqi, Mizhi, Shenmu, Zizhou and Daniudi units, have been discovered and proved in Shanbei Slope belt up to now. These units have linked with one by one as a huge whole, informally called as Qilingou Gas Field. There are five sets of gas-containing formations in these units, which covers an area of 41,800km2 and possesses of over 4×1012m3 of estimated gas reserves in place. The special geological conditions of stablely sedimentary cratonic basin provide a nice guarantee for gas generation, migration, accumulation and preservation during Paleozoic Era. Abnormally high-pressure hydrocarbon that generated from Carboniferous and Permian high-temperature and high-pressure gas source rocks expels sedimentary water from the original reservoirs and fills in all of available reservoir space during migrating and emplacing into the overlapping and underlying reservoirs, and thus this huge-scaled gas field forms.