The isobaric vaporliquid equilibrium data for binary systems of 1,3,5-trichlorobenzene (1) + 3,5-dichloroaniline (2) and 3-chloroaniline (1) + 3,5-dichloroaniline (2) were measured experimentally under pressures of 20.00, 60.00 and 101.20 kPa using an inclined ebulliometer. Thermodynamic consistency of the vapor-liquid equilibrium data was tested by means of the Herington semiempirical method, and the isobaric vapor-liquid equilibrium data were correlated with three activity coefficient models, which were Wilson, NRTL and UNIQUAC. The energy interaction parameters were acquired by a nonlinear least-squares regression method for the three thermodynamic models. Results indicate that all the three activity coefficient models can describe the measured isobaric vaporliquid data acceptably. The isobaric vapor-liquid equilibrium data determined in the present work are important in the design and operation for purification of 3,5-dichloroaniline by distillation.