Abstract: Acetic acid is an important basic chemical raw material, and the acidic wastewater generated during its production requires efficient recovery. To address the problems of the relative volatility of the water + acetic acid system being close to 1, as well as the high energy consumption and low separation efficiency of conventional distillation, this study employed a new ionic-liquid-based extractive distillation process. First, thirty-six commercially available ionic liquids were screened using the conductor-like screening model for real solvents (COSMO-RS), and 1-ethyl-3-methylimidazolium chloride (EMIMCl) was selected as the extractant. Isobaric vapor-liquid equilibrium data of the water (1) + acetic acid (2) + EMIMCl (3) ternary system were experimentally measured and correlated using the non-random two-liquid model (NRTL). On this basis, an extractive distillation process was constructed in Aspen Plus, and sensitivity analyses were performed for key operating parameters. The results showed that increasing the concentration of EMIMCl significantly enhanced the relative volatility of water with respect to acetic acid, and excess enthalpy analysis indicated that EMIMCl interacted more strongly with acetic acid than with water, providing a thermodynamic explanation for the vapor-liquid equilibrium results. After sensitivity analysis and determination of suitable operating conditions, high-purity water with a mass fraction of 0.9963 was obtained at the top of the extractive distillation column, while acetic acid with a mass fraction of 0.9991 was obtained via flash separation of the bottom mixture of acetic acid and EMIMCl. The unit energy consumption was 2.99 MJ·kg⁻¹ , and the recovery rate of the ionic liquid reached 99.99%. This study provides a theoretical basis for the high-value recovery of acetic-acid-containing wastewater and process intensification.