This paper is the result of geological survey engineering. Objective Multiple sets of marine source rocks such as Cambrian–Ordovician, Silurian, Carboniferous–Permian, etc. are widely distributed in the northern Guizhou area of China, which have a good source–reservoir–caprock combination vertically and are of great natural gas resource potential and prospects for exploration and development. In order to better assess the natural gas resources in the area, on the basis of the discovery of the "four–story" composite natural gas reservoir in Anye 1 Well of the Anchang syncline in the Wulingshan area, northern Guizhou, this paper discusses the genesis of the Shiniulan Formation gas reservoir in the Anchang syncline. Methods Field geological works and indoor studies, geological probes and geochemical analyses, macroscopic observations and microscopic techniques, as well as literature researches were carried out. Results It is considered to be a slit–type carbonate gas reservoir, the gas is mainly derived from the underlying Longmaxi Formation, and the multiple stage tectonic movements in the area provided the driving force for its accumulation. Conclusions This research is significant for natural gas resources assessment of the region, and is also helpful for enriching and developing the theory of hydrocarbon accumulation in complex structural belts.