The SAFT equation of state is applied to the correlation of thermodynamic properties of the binary systems consisting of water–ethanol, water–carbon dioxide and ethanol–carbon dioxide. Based on this, the liquid phase compositions of ternary system are calculated from vapor phase compositions using SAFT equation in the range of 308.15–338.15 K and 10.1–17.0 MPa, in which carbon dioxide acts as a supercritical extraction solvent. The phase equilibria predicted by SAFT agree with the experimental data from literatures accurately.