The Electrolyte-UNIQUAC-NRF model proposed by Haghtalab and Peyvandi, Fluid Phase Equilib., 281, 2009 is modified and extended to represent the excess Gibbs energy function of multicomponent electrolyte solutions. Using the experimental mean activity coefficient of aqueous binary electrolyte systems in the extensive domain of temperature and molality, the adjustable temperature dependent parameters are obtained for the several binary electrolyte systems. Furthermore, the osmotic coefficient and vapor pressure of some binary systems are predicted at the wide range of temperature and molality using the adjustable parameters. Having the binary interaction parameters, the solubility of electrolytes in ternary aqueous electrolyte solutions are predicted at 298 K and the higher temperatures so that the phase diagram of the salt solubility are obtained for the several ternary aqueous-salt systems. The results of the solubility, osmotic coefficient and vapor pressure for the electrolyte systems demonstrate that the generalized Electrolyte-UNIQUAC-NRF model can be successfully applied for prediction of the thermodynamic properties of multicomponent electrolyte systems with very good accuracy.