An organic salt choline chloride (ChCl) was introduced in ethylene glycol (EG) for improving the entrainer performance for ethanol dehydration by extractive distillation. The mixed solvent EG + ChCl with molar ratios of 8:1, 4:1, 2:1, and 4:3 were tested through vaporliquid equilibrium (VLE) measurement for the quaternary system water + ethanol + EG + ChCl at 101.3 kPa. Data were also measured for the ternary system water + ethanol + ChCl. VLE behavior of the quaternary system was modeled successfully using the NRTL equation. The mean absolute deviations for the quaternary data were 0.24 K for equilibrium temperature and 0.0041 for vapor mole fraction of ethanol, while deviations for the ternary data were 0.15 K and 0.0032. As compared with EG alone, the existence of ChCl in the mixed solvent decreases the activity coefficient of water and increases the activity coefficient of ethanol, both leading to the enhancement of the relative volatility of ethanol to water. The azeotrope of water + ethanol can be removed with the addition of EG + ChCl 4:3 at a solvent mass fraction of 0.062, showing favorable entrainer performance for ethanol dehydration by extractive distillation.