Abstract: The solubilities of SDBS in ethanol-water and in ethanol-NaOH aqueous mixed solvent were measured at 298.15K to 318.15K.The experimental data showed that solubility of SDBS increased with rising temperature and the effect of NaOH on the solubility of SDBS was little. A thermodynamic solubility model of the electrolyte in the mixed solvent was proposed.The solubility of SDBS in the ethanol-water (or NaOH aqueous) or in the isopropanol-water (or NaOH aqueous) at 298.15K to 318.15K was calculated with the solubility equation deduced from this model.The agreement between calculated values and experimental data was good.