CO₂ reinjection into oil and gas reservoir can enhance recovery effectively. Researched are thermal properties and pipeline transportation technology of CO₂, investigated are domestic and foreign CO₂ pipeline transportation technologies and experience, used are design concepts and calculation methods of oil and gas pipelines for reference, analyzed are characteristics of CO₂ low critical point and discussed are transportation technologies for such phase state as gas phase, liquid phase and supercritical phase of CO₂ mixture. According to single-phase flow transportation condition, compared are transportation distances of CO₂ mixture single-phase flow under the conditions of different flow rates and different diameters. Calculation results show that supercritical phase pipeline has the farthest single-phase flow transportation distance and gas and liquid phase pipeline has the shortest transportation distance. In a given flow rate and transportation distance condition, different transportation means will require pipelines with different diameters, gas phase transportation means requires pipeline with the largest diameter and supercritical transportation means requires pipeline with the smallest diameter. Achievements obtained from CO₂ pipeline transportation technology researches can provide basis for economic research of different CO₂ pipeline transportation processes.