Abstract: The study on the static and dynamic data of the biotic reef gas reservoir in Changxing formation of A gas field shows that the permeability ratio in this area is very poor. In order to accurately simulate the flow of fluid in the gas reservoir, 3D fracture modeling is carried out by comprehensively using fracture research results such as core, well logging, seismic and dynamic data. The results show that: ① The fracture development scale is mainly small and micro scale. ②There are three groups of natural fractures, among which the NW-SE fractures are the most developed, accounting for 56% of the total fractures, with an average fracture opening of 48.9 um; ③ Vertically, high-quality reservoirs contain natural fractures with high conductivity. On the plane, the fracture distribution is mainly controlled by the geomorphic form of the local area. The fracture characterization based on multi-scale fracture coupling is of guiding significance for well location adjustment and reasonable production allocation.