Abstract: Isobaric vapor-liquid equilibrium (VLE) data of sec-butyl acetate-N,N-dimethyl formamide and sec-butyl acetate-acetonitrile binary systems were measured at 101.3 kPa with an Ellis vapor liquid equilibrium still, and the experimental data passed the thermodynamic consistency test using the Herington method. Moreover, the experimental equilibrium data were correlated by Non-Radom Two-Liquid(NRTL), Wilson and Universal Quasi-Chemical(UNIQUAC) activity coefficient models. The results show that all of three models (especially the NRTL model)have good agreements with the experimental data. The binary vapor-liquid equilibrium phase diagrams of sec-butyl acetate-N,N-dimethylformamide and sec-butyl acetate-acetonitrile can be obtained which provide reliable data for distillation design.