Abstract: The perforation of a gas-gathering pipeline occurred in short time of a certain platform in Sichuan-Chongqing shale gas field. For finding the reasons of gas pipeline corrosion failure, the corrosive condition was analyzed at first. Then, combined with the physical and chemical properties of materials and the test results of the morphology and composition of corrosion products, the conclusions were gotten. CO₂ in feed gas and sulfate-reducing bacteria(SRB) in flow back fluid were both main factors for the corrosion failure of gas-gathering pipeline, which participated in corrosion reaction and the corrosion scale mainly composed of FeCO₃ and FeS was formed. With the effect of CO₂ and SRB metabolism, pitting of gas-gathering pipeline developed rapidly.