Abstract: For CO₂ transportation, as an intermediate link in the construction of large-scale carbon capture, utilization and storage projects, pipeline transportation is the preferred. Therefore, the economic evaluation model of CO₂ pipeline transportation is the basis for evaluating its return on investment and optimizing the parameters of pipeline transportation. By comparing and analyzing the calculation formula of CO₂ pipeline diameter, an economic evaluation model was established and thereby, the economic evaluation of pipeline diameter was performed based on a case of supercritical CO₂ pipeline engineering. The results show that the unit cost of supercritical CO₂ pipeline transportation decreases first and then increases with the increase of the pipeline diameter. For the pipeline with a transport capacity of 1×10⁶ t/a and a length of 200 km, the unit transportation cost of CO₂ is the lowest at the pipeline diameter of 240 mm. Since the calculation result of the Vandeginste pipeline diameter formula is close to the theoretical optimal pipeline diameter, the Vandeginste pipeline diameter formula is recommended for the calculation of the pipeline diameter in the actual projects. However, the pipeline cost saved at a nominal diameter of 200 mm is far greater than the increment of energy consumption, and thus the annual cost in this case is the minimum. In addition, the unit transportation cost decreases with the increase of transportation distance, and the unit cost trends to be stable when the distance is longer than 200 km. Therefore, the research results could provide scientific basis and reference for the decision-making concerning the economic pipeline transportation of CO₂.