Abstract: The exploitation way of Orinoco heavy oil reservoir is natural pressure failure method. Exploitation process has the characteristics of high oil production, low gas production and low pressure, and the "foam oil" will appear in the exploitation process. In order to study the stability and rheology of foam oil in the formation, we used the self-developed high-temperature and high-pressure foam oil distributor to configure foam oil and research the effects of viscosity, temperature, salinity and dissolved gasoline ratio on foam oil stability and measured the rheological properties of the foam oil by rheometer and core flow device, respectively. The experimental results show that with the increase of the viscosity of degassed crude oil, the half-life of foam oil becomes longer and the stability is better; the higher the temperature, the worse the stability; the higher the dissolved gas oil ratio, the better the foam oil stability; the effect of salinity on stability is not obvious; Orinoco foam oil has the property of shear thinning and slight thixotropy; in porous media, the viscosity of foam oil decreases firstly and then increases with the increase of injection pressure, and the fluidity of foam oil is significantly higher than that of degassed crude oil under the same pressure gradient. This study improves people's understanding of foam oil performance and is beneficial to further improve foam oil performance research.