Experimental studies and thermodynamic modeling for the separation of aromatic compounds from a complex mixture of hydrocarbons have been carried out. The sample used in this work is the main material for producing lubricating oils, and the solvent used for extraction of aromatic components is a new selective solvent which has unique specifications in comparison with conventional solvents such as furfural. This modeling is based on the method of Ruzicka for making model molecules. The parameters required for modeling were obtained, and then liquid-liquid equilibrium calculations were done and compared with the experimental data. These calculations were also carried out using published parameters for the vapor-liquid equilibria of the components involved in the mixture. The results have been compared with the previous calculations as well as with the experimental data, and good agreement was found.