The development of new technologies for synthesizing xylene from methanol has great significance in China, as the coal-based chemical products have been redundant and homogeneous seriously. Due to the challenge of high energy consumption in the chemical separation process, a multi-objective optimization research was carried out in the separation of non-aromatic hydrocarbons, benzene, toluene and xylene mixture using Aspen Plus and Matlab software in this work. The traditional two-column sequence separation process and the dividing wall column process had been simulated and optimized by NSGA-II algorithm respectively. Total annual cost (TAC), energy consumption per product flow rate (GEC), the productivity of benzene-toluene and the productivity of xylene were set as objective functions. The results showed that effect of the reflux ratio on TAC was critical. The two separation processes were compared based on the lowest TAC under the premise of satisfying the constraints. The results indicated that the lowest TAC, heat transfer cost and GEC of the dividing wall column process were reduced about 7.7%, 16.1% and 26.3% in comparison with the two-column sequence process, respectively. It implied that the dividing wall column process would be the best sustainable process in xylene production with lower TAC and GEC.