Abstract: To clarify the under-deposit corrosion behavior of 316L stainless steel pipelines for CO₂ transport, electrochemical tests and high-temperature and high-pressure immersion tests for 316L stainless steel were carried out in a simulated under-deposit corrosion environment. The results showed that sand and CaCO₃ deposits increased the under-deposit corrosion sensitivity and reduced the re-passivation performance of 316L stainless steel. Sand deposits caused sub-stable pitting corrosion, and thick CaCO₃ deposits reduced the free corrosion potential of the steel. 316L stainless steel had a good under-deposit corrosion resistance at 100 ℃ and 5 MPa CO₂. But the steel was at a risk of under-deposit corrosion when the deposits formed a suitable crevice with the material. It is necessary to pay attention to prevent and remove deposits on 316L stainless steel pipeline in the corrosion environment of high-temperature and high CO₂ partial pressure.