【正文】 rile and ethyl acetate in the water, Ma Wenchan [3]adopts the method of liquidliquid extractive which use water as extractive agent to separate acetonitrileethyl acetate ,the product of ethyl acetate can achieve %,but acetonitrile mixed with abundant water, so recovery of acetonitrile is very difficult. According to our knowledge, no authors have studied the separation of acetonitrile ethyl acetate by extractive distillation. In recent years, the application of extractive distillation[46]for the separation of closeboiling mixture has been widely accepted and mercialized over the conventional distillation which may also be feasible but with substantial column investment. However, due to the problem of selectivity and solubility are often inconsistent in single solvent, limit its application and development. Mixed solvents guarantee high selectivity, and improved solubility at the same time through the bination of main solvent and vice solvent[7]. In recent years, mixed solvents are applied more and more in extractive distillation[811] . This paper is devoted to the study of the separation of the mixture acetonitrile– ethyl acetate by using extractive batch distillation which extractive solvent is mixed solvents. First, the selection of an adequate extractive solvent is presented based on the puter aided molecular design of solvents for separation processes bining group contribution methods with graph principle. Later, results of several laboratory batch tests are presented serving for determination of the most effective solvent. Finally, the main operating parameters of extractive distillation process were optimized. 2. Entrainer selection for the separation of acetonitrile– ethyl acetate mixture The extractive distillation is generally applied to the separation of closeboiling mixtures, which by conventional distillation is difficult to separate. The design and optimization of extractive distillation is more plex than that of the conventional distillation when considering the selection of suitable solvent to enhance the separation. In the extractive distillation, the selection of a suitable solvent is fundamental to ensure an effective and economical design. Currently, the solvent selection can be effectively handled by the assistance of the puteraided molecular design (CAMD) approach. The candidates as extractive solvent were chosen by the graph principle and group contribution method bined with puteraided molecular design. Firstly, based on Modfied UNIFAC method, the functional groups systematically are classified and preselected according to some rules, and then the automatic bination of groups is pleted by using a graph algorithm. The group contribution methods are used to get the basic physical and thermal properties. The basic molecular library is formed by using several limited rules of basic physical properties. In the stage of solvent screening, the molecules in the basic molecular library are used directly. The candidate solvent molecules are obtained by using the solvent constraint and the appropriate solvent molecules can be determined by using the refined calculation or checking property library.