Abstract: The present invention provides a method of restraining gas channeling phenomena during CO2 flooding process in the low-permeability fractured reservoirs through two-stage gas channeling blocking treatment so as to increase oil recovery. The two-stage gas channeling blocking technology includes first-stage gas channeling control to block off fractures using high-strength gel which is formed by natural modified polymeric materials, and second-stage gas channeling control to block off relatively high-permeability layers in the low permeability matrix using aliphatic amine. The gas channeling is effectively controlled and the swept volume is enlarged during the process of CO2 flooding in low permeability fractured reservoirs, and the oil recovery is greatly improved by two-stage gas channeling blocking technology.