Oil and gas production often encounters the presence of corrosive gases in sewage and the flow rate reaches the erosion rate. In this case, the sewage pipe has been seriously corroded, seriously affecting the safety of operation. In this paper, the influence of CO2 and O2 in water and the mixture of CO2 and O2 on the corrosion of N80 steel was analyzed by indoor simulation experiment using high temperature and high pressure reactor under the erosion rate of sewage. The results show that the effect of corrosive gases on the corrosion of N80 steel is in the order of O2+ less CO2 > O2 > CO2+ less O2 > CO2. Due to the erosion effect of sewage, there is a small depression on the surface of N80 steel, which increases the corrosion surface. At the same time, the diffusion rate of CO2, O2 and CO2 and O2 mixture gas is accelerated, which promotes the hydration of corrosion gas, reduces the density and distribution range of corrosion product layer, and speeds up the diffusion of these corrosion gases in the corrosion product film. It promotes the local corrosion of N80 steel and makes the corrosion change from uniform corrosion to local corrosion.