To overcome the poor stability of CO₂ foam under high-temperature and high-salinity conditions，sodium α-olefin sulfonate（AOS，anionic）and octylphenol polyoxyethylene ether（OP-40，nonionic）were formulated as a mixed foaming agent， and a temperature- and salt-tolerant terpolymer（AMPA）was introduced as the foam stabilizer. The optimal composition（surfactant concentration and AOS/OP-40 mass ratio）was screened using the Waring-blender method. Foam performance was then evaluated at 80 ℃ and 100 000 mg/L salinity and benchmarked against a conventional HPAM-stabilized system. In parallel，molecular dynamics（MD）simulations were conducted by constructing a gas/liquid interfacial model to elucidate the interfacial synergy between the anionic-nonionic surfactant mixture and AMPA，and to rationalize the performance differences between AMPA and HPAM in modifying the interfacial properties. When the mass ratio of AOS to OP-40 being of 1∶1，total surfactant content being of 1.0%，and AMPA dosage being of 0.35%，the optimized AMPA-stabilized foam system achieved a foam volume of 420 mL and a drainage half-life of 35.6 min. Under the same harsh conditions，the drainage half-life of the AMPA system was 2.3 times that of the HPAM-stabilized foam. MD simulations revealed that AMPA exhibited stronger synergistic interactions with surfactants，resulting in thicker hydration and gas adsorption layers，reduced liquid film drainage rate and delayed gas diffusion. Additionally，AMPA significantly decreased interfacial tension and formation energy，leading to more stable interfaces and stronger foam stability. These findings provide a theoretical foundation for the molecular design of next-generation foam stabilizers.