The formation of low-viscosity emulsions is a vital method for viscosity reduction of crude oil. Naphthenic acids, which are present in crude oil, are potential surface-active substances. Tertiary amines with CO2 response can be self-assembled in situ with the naphthenic acids in the crude oil to form a surfactant, which can emulsify the heavy crude oil and water to form an emulsion. The emulsion can be easily demulsified in the presence of CO2. N,N-Dimethylbutylamine, N,N-dimethyloctylamine, and N,N-dimethyldodecylamine were used to prepare heavy crude oil emulsions in this work. This convenient emulsification and demulsification approach provides a new concept for pipeline transportation of heavy crude oil.