Maine Carbon Capture, Utilization and Storage (CCUS) is one of the effective methods to solve the problems caused by the excess emission of CO₂. However, the pipelines face serious corrosion problems in the process of CO₂ transport. Aiming at marine corrosion problems under supercritical CO₂ conditions, this work investigated the corrosion behavior of A106 carbon steel with different water contents and temperature by mass loss, scanning electron microscope (SEM), X-ray diffractometer (XRD) and three-dimensional stereoscopic microscope. Results indicate that the corrosion rate of A106 steel increased with the increase of water content in CO₂ environment at 10 MPa and 35 ℃. When the water content exceeded 2000 μL/L, the corrosion rate was significantly accelerated. A106 steel reached the maximum corrosion rate, i.e., 0.16 mm/a at the water content of 3000 μL/L. However, the localized corrosion rate of A106 steel was the highest with the value of 0.73 mm/a at the water content of 2000 μL/L. In the CO₂ environment at 10 MPa, the corrosion rate of A106 steel decreased from 25 to 60 ℃ and then increased with the increase of temperature. At 60 ℃, the corrosion rate reached a minimum value, i.e., 0.025 mm/a. Therefore, temperature and water content are the key factors affecting the corrosion of steel materials in supercritical CO₂ environment.