In this study, to overcome the challenge of poor foam stability in high-temperature and high-salinity reservoirs, a novel temperature- and salt-resistant terpolymer foam stabilizer (AMPA) was synthesized via free-radical polymerization of acrylamide (AM), 2-acryloylamino-2-methyl-1-propanesulfonic acid (AMPS), and acrylic acid (AA). The compound was blended with anionic surfactant sodium α-olefin sulfonate (AOS) and nonionic surfactant octylphenol polyoxyethylene ether (OP-40) to enhance CO? foam stability at 80?°C and 100,000?ppm salinity. Experimental results demonstrated that the AMPA foam system achieved superior foam volume (420 ?mL) and half-life (35.6 ?min) at a 1:1 mass ratio of AOS to OP-40, with a total surfactant concentration of 1? wt% and an AMPA concentration of 0.35 ?wt%. Compared with the partially hydrolyzed polyacrylamide (HPAM) system, the foam half-life with AMPA was extended by 2.3 times under high-temperature and high-salinity conditions. Molecular dynamics simulations revealed that AMPA exhibited stronger synergistic interactions with surfactants, resulting in thicker hydration and gas adsorption layers, reduced liquid film drainage rate, and slower gas diffusion. Additionally, AMPA significantly decreased interfacial tension and formation energy, leading to more stable interfaces and enhanced foam stability. These findings provide a theoretical foundation for the molecular design of next-generation foam stabilizers.