Ethyl Acetate (EtAc) is an important industry solvent in many fields such as essence,paint,resin,et.al [1].In this paper,the separation of ethyl aeetate-ethonal azeotropic systerm using mixed solvent (N,N-dimethylforrnaaide (DMF)-methylsulfoxide (DMSO)) by batch extractive distillation was studied.The mixed solvent is a new type of extraction agent which is made up by two kinds of single solvents in a certain proportion [2].Its main feature lies in the fact that it can dissolve the contradictions between selectivity and solvency in single solvent and obtain better effects.