The separation of benzene and cyclohexane by extractive distillation was intensified with the addition of ionic liquid (IL) as entrainer. The IL [EMIM][BF4] was chosen in terms of selectivity and solvent capacity. Vapor-liquid equilibrium (VLE) experiments using pure N-methyl-2-pyrrolidinone (NMP), the NMP and IL mixture, pure sulfolane, and the sulfolane and IL mixture, were conducted. The VLE results indicated that NMP is more suitable than sulfolane, due to the poor miscibility of sulfolane and key components in a whole concentration range. Moreover, the addition of IL into NMP can slightly improve the relative volatility of cyclohexane to benzene with the NMP and IL mixed entrainers, but the concentration of volatile NMP in vapor phase decreases obviously with the addition of IL. Based on the experimental VLE data, the UNIFAC-Lei model was applied, and the corresponding interaction parameters were obtained. The extractive distillation process was designed and optimized with the equilibrium stage model, in which the UNIFAC-Lei model parameters were implemented. The simulated results indicated that the extractive distillation process was intensified by the addition of IL in saving energy and entrainer usage. Moreover, no extra equipment expense is needed compared with benchmark solvent.