Three ionic liquids (ILs)(1-ethyl-2,3-dimethylimidazolium acetate, [EMMIM][AC]; tributyl-methylammonium acetate, [N-4,N-4,N-4,N-1][AC]; and tetraethylammonium acetate, [N-2,N-2,N-2,N-2][AC]) were chosen. The vapor-liquid equilibrium (VLE) data of ternary mixtures (acetate + ethanol + IL) were measured at 101.3 KPa. NRTL equation was used to correlate the data. From NRTL model, for [N-2,N-2,N-2,N-2][AC], [EMMIM][AC], and [N-4,N-4,N-4,N-1][AC], minimum mole fractions for completely eliminating azeotrope are 0.015, 0.020 and 0.022, respectively. From the average relative volatility and sigma-profiles, it can be obtained that the separation ability order is [EMMIM][AC] > [N-2,N-2,N-2,N-2][AC] > [N-4,N-4,N-4,N-1][AC].