A composite gel was prepared for plugging CO2 channeling,which is a serious problem for enhanced oil recovery with CO2.A composite gel which is one of the materials for successful control of CO2 channeling during CO2 injection process was studied in this paper.SEM and nano particle size analysis were used to describe this materials microstructure.Its effect on CO2 channeling control was evaluated with core flow experiments.Both the rheological test and core plugging experiments indicated that both acrylamide monomer concentration and reaction pressure had positive influences on gel properties.The gel system with an acrylamide monomer concentration of 2% and 5% sodium silicate was proved to have excellent strength,elastic and plugging efficiency,which confirmed huge development potential and wide application of the composite gel system.The high-pressure acid environment arising from the CO2 injection not only reacts with solid silicate to form silicic acid gel,but also facilitates efficient polymerization.