With the growth of petroleum energy demand and the depletion of conventional oil and gas resources, the major oilfields in China have entered the high water-cut development stage. The oil displacement efficiency of CO2flooding technology is limited due to issues such as the significant gas-oil mobility ratio and high interfacial tension; meanwhile, traditional high-concentration surfactants have drawbacks including high cost and poor compatibility. To address these problems, this study proposes a 0.15 wt% SDBS/AEO-7 (1:1) low-concentration compound system, and systematically investigates its synergistic enhancement mechanism for CO2flooding through contact angle, interfacial tension, viscosity, and slim-tube displacement experiments.The results show that, relying on the electrostatic-hydrogen bond synergistic mechanism, this system achieves an ultra-low interfacial tension of 0.0015 mN/m, with a salinity tolerance of up to 80 g/L. The increase in interfacial tension is less than 15% at 100℃. For medium-permeability cores (240 mD, pore throat 5–10 μm), the oil displacement efficiency reaches 90.8%, which is 11% higher than that of single CO2 flooding. This system breaks through the bottleneck of traditional CO2flooding and provides a new path for increasing production in high water-cut reservoirs.