With the development of the economy, the demand for energy in our country is increasing. At the same time, the increase in carbon dioxide emissions has brought about a series of environmental problems. The study found that CO2 flooding can improve the physical properties and crude oil recovery rate, and realize geological storage for carbon dioxide with supercritical CO2 injected into heavy oil reservoirs. Therefore, CO2 flooding is of high value in heavy oil reservoirs development. In this paper, the numerical simulation of supercritical CO2 flooding in heavy oil reservoirs was carried out based on the research of basic geology, comprehensive logging interpretation and 3D geological model, with the reservoir of Suizhong 36–1 oilfield being selected as the research object, and the physical properties of the reservoir were analysed after CO2 flooding. The physical property change law following the injection of CO₂-driven thick oil was investigated from three perspectives: the bottom, top, and lateral aspects of the reservoir. We observed the effect of CO2 flooding after analyzing the influence of CO2 flooding on oil saturation, carbon dioxide saturation and water saturation of the reservoir. The results show that, (i) gravity overburden exits in the process of CO2 flooding; (ii) combining with simulation of vertical lateral oil saturation, the CO2 seepage direction under buoyancy is inclined upward, and thus oil recovery can be improved more effectively by selecting lower terrain for injection Wells in the same objective interval. (iii) CO2 flooding can change the seepage mechanism of reservoir, with CO2 having a much higher diffusion coefficient than water, making it more effective at displacing crude oil initially. In conclusion, this study provides a theoretical basis for enhancing oil recovery in Suizhong 36–1 oilfield through CO2 flooding under the condition of high water content.