Low permeability reservoirs in Shengli oilfield are characterized with deep burial depth（＞3000 m），high temperature （>120 ℃），and strong heterogeneity. Aiming at the problems of low sweep efficiency of CO₂ flooding and poor profile control performance of conventional foam，a highly stable supercritical CO₂ foam system with zwitterionic surfactant（HSD）and modified SiO₂ nanoparticles as foaming agents was developed. The foaming performance and temperature resistance of the system at high temperature were studied. The effects of nano-SiO₂ on the rheological properties，plugging properties and profile control performance of supercritical CO₂ foam system were evaluated respectively. Finally，the stabilization mechanism of nanoparticle reinforced supercritical CO₂ foam was discussed. The results showed that the highly stable supercritical CO₂ foam system had good foaming performance and temperature resistance. With increasing dosage of nanoparticle in the system，the half-life of foam gradually increased first and then decreased. At 110 ℃，0.5% nanoparticle could increase the half-life of foam drainage from 17 min to 40 min，and then the stability was improved by nearly 2.5 times. At the same shearing rate，the apparent viscosity of the system increased with the increase of nanoparticle concentration，and then the consistency coefficient increased from 0.073 to 1.220. In the core flooding experiment，the steady-state apparent viscosity of foam in porous media increased with the increase of nanoparticle concentration，thereby increasing the plugging strength. Supercritical CO₂ foam was stacked and discharged in“granular”shape. The foam size was 10—20 μm. Supercritical CO₂ foam had good profile control and displacement performance，which could block high permeability channels and compel subsequent injected CO₂ into low permeability matrix，thus improving oil recovery. Surfactant molecules adsorbed on the surface of nano-SiO₂ ，which made it have interfacial activity，and then nano-SiO₂ adsorbed on the gas-liquid interface to improve the stability of foam.