Abstract: In CO₂ transmission, two common liquefaction processes (i.e., low-temperature low-pressure liquefaction process and normal-temperature high-pressure liquefaction process) require the storage equipment with extremely high resistance to low temperature and high pressure. In order to find an economic and reasonable CO₂ transmission mode, this paper simulated and compared several pipeline transmission processes with the HYSYS software, aiming to work out an improved liquefaction process which has lower requirements for temperature and pressure. The results show that, in the proposed four types of transmission modes, i.e. gas-phase, liquid-phase, dense-phase and supercritical-state, the dense-phase mode is superior to the widely used supercritical-state mode. The improved liquefaction mode is suitable for dense-phase transmission, without the defects of low-temperature low-pressure liquefaction process and normal-temperature high-pressure liquefaction process. Moreover, the improved mode is less energy-consuming and can ensure safe and economic storage in tanks for which no high performance is required. The CO₂ liquefied with this improved process is easy to store, providing a reference for the CO₂ tank design.