In this article, Aspen Plus was used to simulate a process for separating the mixture of decanol + undecanol + tetradecane + pentadecane to obtain decanol + undecanol product and tetradecane + pentadecane product. Aqueous ethanol solution and octadecane were chosen as potential extractants. First, the liquid-liquid equilibrium (LLE) data of the four quaternary systems {ethanol (1) + decanol (2) + tetradecane (4) + water (6), and ethanol (1) + decanol (2) + pentadecane (5) + water (6), ethanol (1) + undecanol (3) + tetradecane (4) + water (6), ethanol (1) + undecanol (3) + pentadecane (5) + water (6)} and the six-component system {ethanol (1) + decanol (2) + undecanol (3) + tetradecane (4) + pentadecane (5) + water (6)} were obtained at 293.15, 298.15, and 303.15 K under atmospheric pressure. The UNIQUAC model was used to regress the LLE data of the four quaternary systems to obtain the binary interaction parameters, which were used to predict the LLE data of the six-component system. The results showed that the predicted and experimental data were in great agreement. Second, the LLE data of the sevencomponent system {ethanol (1) + decanol (2) + undecanol (3) + tetradecane (4) + pentadecane (5) + water (6) + octadecane (7)} were obtained at 303.15, 308.15, and 313.15 K under atmospheric pressure, and the binary interaction parameters involving the component octadecane were obtained by data regression using the UNIQUAC model. Finally, a 2500t/a process of separating the mixture of decanol + undecanol + tetradecane + pentadecane was simulated in Aspen Plus with these regressed binary interaction parameters. On optimization, 99.80 wt % decanol + undecanol product and 99.76 wt % tetradecane + pentadecane product were obtained.