Four surfactants were chosen as foaming agent in this study ，including nonionic surfactants N-NP- 15c and N-NP-21c，newly synthesized anionic-nonionic surfactants N-NP-15c-H and N-NP-21c-H ，whose nonionic group was ethylene oxide（EO）and anionic group was sulfonic group. The performance of surfactants as CO ₂ foaming agent was investigated at high temperature and pressure conditions using a HTHP visualization foam meter with agitator. The effect of various influence factors on foam stability，including surfactant concentration ，water salinity，Ca²⁺ concentration，temperature and pressure，was studied. Experiment results showed that the foam performance of N-NP- 15c-H was the best ，whose foam volume was81.6 mL and half-life was 10.8 min at 125℃ with 0.7% foaming agent dosage，10MPa pressure and50g/L NaCl concentration. The foam volume and half-life of CO₂ foam first increased and then decreased with increasing mass fraction of surfactant ，and the optimum mass fraction was 0.7%. High temperature and high salinity（or Ca²⁺ concentration）were not conducive to the stability of CO₂ foam，while the increase of pressure could improve the performance of CO₂ foam significantly. When the pressure increased from 5 MPa to 12MPa，the foam volume increased from87.9 mL to165.8 mL and foam’s half-life increased from34.5 min to 295.2 min.