Abstract: To determine the favorite state of CO₂ in pipeline transportation, changes of density, kinematic viscosity and mass heat capacity with temperature and pressure are analyzed for their physical properties. The results show that CO₂ in the supercritical state is more suitable to the pipeline transportation. Starting from the hydraulics and thermodynamics, Hysys software is used to simulate pipeline transportation conditions where CO₂ is in different states to the obtain change curves of pipeline transportation pressure drop vs pipeline length, fluid temperature vs pipeline length and heat loss vs pipeline length and calculate the effective transportation distances of CO₂ in different states. Analog computation is calculated for CO₂ pipeline transportation cases respectively with nitrogen and methane impurities. The results show that the impurities almost have no effect on gaseous and supercritical CO₂ transportation pipeline but play a larger effect on the CO₂ liquid pipelines and nitrogen plays a larger effect than methane under the same conditions.