In order to improve the foam performance under harsh conditions of high-temperature and high-salt oil reservoirs, the synergistic effect of the binary system of dodecyl diphenyl ether disulfonate (DDBS) and cocoamidopropylamine oxide (CAO) was studied. The critical micelle concentration (CMC), surface tension and foam performance were tested. The results showed that the interaction parameters of the two substances in the monolayer adsorption at the interface and micelles were between -3 and -7, showing a moderate degree of synergism. Compared with the single surfactant, the binary system significantly reduced the CMC and surface tension, and increased the saturation adsorption capacity, thus improving the foam performance significantly. When the optimal molar ratio n(DDBS):n(CAO)=6:4 was selected, naming SHY-1, which had a wide salinity adaptation range. It exhibited good foam performance at a salinity of 0-158308 mg/L and calcium and magnesium ions of 0-10000 mg/L. The foam was generated in situ in porous media at 105℃, with a apparent viscosity of 180 mPa?s, effectively sealing the channeling. DDBS/CAO surfactants can enhance the foam properties, which brings broad prospects for the application of foam in high-temperature and high-salt reservoirs.