Based on emulsion polymerization and free radical polymerization methods, using styrene and azobisisobutyronitrile as the main reagents, active polystyrene microspheres were prepared. These were used to initiate the reaction of acrylamide (AM), the CO2-responsive monomer dimethylaminoethyl methacrylate (DMAEMA), the stability crosslinker N,N’-methylenebisacrylamide, and the acid-sensitive crosslinker N,N-diacryloyloxy-bis(2-aminoethoxy)methane to prepare a CO2-responsive gel particle system (CRP) for sealing CO2 channeling pathways in tight oil reservoirs. The structure of CRP was characterized, and its swelling behavior, and CO2 responsiveness were tested. Combined with a high-temperature, high-pressure online NMR displacement system, its ability to enhance CO2 flooding recovery was determined. The results show that as the temperature increases from 30°C to 90°C, the mass swelling ratio of CRP increases from 35.7 to 68.1 times. At 30°C, the median particle size of CRP after swelling equilibrium is 107.2μm, which increases to 118.2μm after contact with CO2, indicating significant CO2 responsiveness. In a tight matrix-fracture dual-media core, after CO2 breakthrough, injecting 0.3 FPV of 0.3% CRP suspension followed by aging for 24 hours and subsequent CO2 injection can enhance oil recovery by 17.43%. The above experimental results demonstrate the feasibility of preventing CO2 gas channeling in tight matrix-fracture dual-media systems.