In recent years, with the increasing demand for carbon capture and storage, CO2 transmission pipeline has become a key support and its large-scale development trend is obvious. Compared with gaseous transmission, long-distance CO2 transmission pipeline using supercritical transmission mode enjoys better economics, but there are significant characteristics such as higher pressure gradient after leakage, higher requirement of pipeline crack arrest toughness, and different consequences as compared to leakage from oil and gas process media. Especially for the supercritical CO2 pipeline leakage issue, due to its density being greater than air, asphyxiation and other characteristics, the analysis on its leakage consequences is increasingly gaining concern and worthy of an in-depth study. At present, relevant pipeline transmission specifications have been released at home and abroad, but there are no explicit requirements on quantitative risk analysis methods and critical threshold indicators for leakage consequences, which are still insufficient for reference in detailed engineering design. Furthermore, there are little discussions on analysis and comparison with experimental results. Based on the phase characteristics of CO2 and the characteristics of supercritical CO2 transmission, the issue of selecting the safety threshold for the consequences of supercritical CO2 leakage is discussed, and an in-depth study of overseas supercritical CO2 pipeline rupture experiments is conducted, and the simulation analysis of the consequences of supercritical leakage is carried out for comparison purposes. The study shows that the molar concentration 4% is recommended as the evaluation concentration value for the evaluation of impact range of CO2 pipeline rupture; the impact range of leakage in overseas large-scale CO2 full-size rupture experiments is larger than the potential impact radius of natural gas pipelines of the same scale; the dispersion range of CO2 pipeline rupture leakage is mainly influenced by the length and outer diameter of the pipeline, and the sensitivity to the impact of pipeline pressure is lower. The results can provide relevant references for supercritical CO2 pipeline engineering design.