Based on the molecular interaction volume model (MIVM), the pair-potential energy parameters B-ij and B-ij of the related binary Sn-Pb, Pb-Sb and Sn-Sb alloy systems were calculated using the infinite dilution activity coefficients gamma(infinity)(i) and gamma(infinity)(j). The activities of components of the Sn-Pb-Sb ternary alloy system were predicted using B-ji and B-ij. Finally, the vapor-liquid phase equilibrium of the Sn-Pb-Sb alloy system was predicted using only the properties of pure components and the activity coefficients, which indicates that Sn can be separated from Pb and Sb by vacuum distillation thoroughly. A significant advantage of the model lies in its ability to predict the thermodynamic properties of multi-component liquid alloys using only two parameters. Moreover, the MIVM is reliable due to it has certain physical meaning from the viewpoint of statistical thermodynamics. (C) 2013 Elsevier B.V. All rights reserved.