Abstract: Direct assessment for internal corrosion of gas pipeline is an important method to assess the internal corrosion of pipelines. In order to improve the applicability and accuracy of direct assessment method for internal corrosion, the influence of CO₂ electrochemical corrosion and particle erosion on the internal corrosion of pipeline was studied through electrochemical testing and numerical simulation. At the same time, the influence of pipeline inclination and liquid holdup on electrochemical corrosion was also analyzed. The research results show that: The influence of electrochemical corrosion on the internal corrosion of the gas pipeline is much greater than that of particle erosion, but the particle erosion can accelerate the electrochemical corrosion. Specifically, the greater the inclination of the pipeline, the higher the liquid holdup, and the more serious the corrosion is. In addition, the long uphill section of pipeline with a smaller inclination is prone to corrosion. Thereby, a new direct assessment method for internal corrosion of natural gas pipelines was proposed and applied to a natural gas pipeline in Panjin. The assessment results show that, compared with the original method, this improved method can more accurately identify the location of water accumulation in the pipeline, compare the corrosion risk of each place of water accumulation, and thus provide new theory and technical support for the assessment of internal corrosion in natural gas pipelines. (