Abstract: The corrosion behavior of 2205 duplex stainless steel under the simulated conditions of the whole process of simulated acidification well completion and production was studied by the combination of electrochemical analysis. The results show that the test steel exhibited slightly uniform corrosion in the formation water containing CO₂. When the CO₂ partial pressure was 4.80 MPa and the experimental temperature was 220℃, the corrosion rate was only 0.002 1 mm·a^-1. The test steel had an obvious ferrite phase selective dissolve corrosion during corrosion in the whole process of acidification well completion, with a lowest corrosion rate of 0.523 6 mm·a^-1, which was much higher than that in the formation water containing CO₂. The test steel was activated in the fresh prepared acid solution, and the corrosion rate was relatively high. In the formation water containing 0.1 MPa CO₂, the anodic polarization zone of the test steel showed a passivation phenomenon, and thus the corrosion rate was reduced significantly.