The isobaric vapor-liquid equilibrium (VLE) data of {N-methylethanolamine + N-methyldiethanolamine (MDEA), N-methylethanolamine + ethylene glycol, ethylene glycol + MDEA} at P = (40.0, 30.0, and 20.0) kPa were investigated in this work. All of the VLE data of the three binary systems were verified to be thermodynamically consistent by both Herington area test and Van Ness point test. At the same time, the universal quasichemical (UNIQUAC), nonrandom two-liquid (NRTL), Wilson, and Margules activity coefficient equations were chosen to correlate the experimental results, deriving the coefficient parameters and estimating the standard correlation values showed that estimated data reached a good agreement with the experimental data in this study.