Abstract：Due to the large viscosity difference between oil and gas and the heterogeneity of oil reservoirs，gas channeling occurs during CO₂ flooding，reducing the sweep efficiency of CO₂. Gel system is an effective channeling blocking agent for the process of CO₂ flooding and is widely used in China and abroad. This paper outlines the channeling blocking mechanisms and research progress of four kinds of gel systems：retardant cross-linked polyacrylamide gels，pre-crosslinked gel particles，two-stage channeling blocking gel systems，and foam gels. Retardant cross-linked acrylamide gels have good mobility and low price，although the gel strength and gelling time are uncontrollable. More importantly，they are not resistant to acid corrosion. Pre-crosslinked gel particles enjoy controllable gelling time and gel strength and are resistant to high temperature and high salinity. Nevertheless，their large particle size prevents them from entering formations with low permeability. The two-stage channeling blocking gel systems，combining the advantages of rigid gels with those of small molecules，can simultaneously block fractures of different sizes. However，their blocking effect decreases when fractures exceed a certain size. Foam gels cause little damage to the formation，although they are not resistant to high temperatures. At present，the gel systems used for gas channeling treatment during CO₂ flooding have the problem of irresistibility to acid corrosion.Keeping gel systems in CO₂ acid environments for a long time stable is the future research direction.