For separation of the azeotropes of n-propanol (NPA) + water and isopropanol (IPA) + water by liquid-liquid extraction, cyclohexanone was selected as the extraction solvent. The liquid-liquid equilibrium (LLE) behavior of the two mixtures (water + NPA + cyclohexanone) and (water + IPA + cyclohexanone) was investigated at temperatures 298.15 and 308.15 K. The LLE phase diagrams of the two mixtures belong to Treybal's type I. According to the measured data, distribution ratio and separation factor obtained by calculation were used to analyze the extraction effect of cyclohexanone. In addition, the NRTL and UNIQUAC models were used to fit the LLE experimental data, and the values of root mean square deviation are smaller than 0.007. Lastly, the analysis of Gibbs energy surfaces was applied to validate the coherence of the fitted binary interaction parameters for the thermodynamic models.