Abstract: The heavy oil O/W emulsions have extremely complicated properties, among which static stability and viscosity are key parameters in selection of available transportation technologies. In this study, O/W emulsions are prepared successfully under high temperature and high salinity conditions by using two kinds of heavy oil and three kinds of emulsifiers to clarify conditions for preparation of emulsions and to identify emulsifiers applicable for different conditions. By studying correlation between the time and changes in viscosity and water extraction rate of O/W emulsion under different preparation conditions, patterns in changes of viscosity and stability of O/W with water contents, stirring conditions, temperatures, salinity and pH can be highlighted to improve the model for prediction of viscosity of O/W emulsions.