Abstract: This paper regards the activity coefficient of salt in mixed solvents with constant composition as a function of vapor-liquid equilibrium data by means of ternary Gibbs-Duhem equation. A verification method including two independent criteria for vapor-liquid equilibrium data of salt containing system is proposed on the bases of thermodynamics and the Debye-Hückel electrolytical solution theory.A ccording to the criteria every experimental point can be verified by the calculation of its vapor-liquid equilibrium data.Not only is this method rigorous in the theory,but also very convenient in the application.Under the condition of fixing the ratio between two solvents it can be used for vapor-liquid equilibrium data verification of various salt-containing systems,whether the systems are isothemic or isobaric,aqueous or non-aqueous,up to saturated or non-saturated.