With the gradual popularization and application of CO2 flooding technology in oilfields, the physical properties of produced fluid, including the stability of the emulsion formed by crude oil and produced water, may be changed, consequently influencing the surface gathering and dewatering processes. In order to investigate the stability changes of heavy oil emulsions and their mechanisms after supercritical CO2 (scCO(2)) flooding, a device that could simulate the scCO(2) treatment condition in the oil reservoir was first designed and used to pretreat the heavy oil. Then, the effects of scCO(2) treatment on the stability of I heavy oil emulsion were investigated by means of a bottle test and microscopic observation. The results revealed that the stability of the emulsion formed by scCO(2)-treated degassed heavy oil was improved. The reason for the stability improvement was then deeply explored from two aspects, i.e., the bulk viscosity and the structural strength of the water-oil interface. On the one hand, it was found that the content of heavy components in crude oil was increased due to the extraction of light components by scCO(2), and the associating degree between asphaltenes was enhanced at the same time, both of which increased the apparent viscosity of the heavy oil and its emulsion, thus lowering the collision probability between dispersed droplets. On the other, with the help of interfacial rheological experiments, the interfacial dilational modulus was found to be increased after scCO(2) treatment due to increased adsorption of interfacial active components in heavy oil such as asphaltenes, indicating that the structure of the interfacial film was strengthened and accordingly the emulsion became a more stable system.