Abstract: The employment of Valentin-Guiochon equation in the chromatographic slope method has been studied. Results of the thirteen binary systems studied show that predictions of vapor-liquid equilibria depend not only on whether the experimental temperature is around the boiling point of the solute or not, but also on the selection of excess Gibbs energy model. Satisfactory prediction results can be obtained at 0-5.5℃ below the boiling point of the solute for UNIQUAC, while, for the Wilson equation, it will be 3-5℃ below the boiling point of the solute if multiple roots do not show up. When multiple roots do appear, the least root will be one of the pair of parameters which can give the satisfactory vapor-liquid equilibr ium prediction.