Abstract: Equilibrium solubility of lithium sulfate-ethanol-water (Li<SUB>2</SUB>SO<SUB>4</SUB>-C<SUB>2</SUB>H<SUB>5</SUB>OH-H<SUB>2</SUB>O) ternary system and refractive index-and-density of saturated solution have been investigated by isothermal equilibrium method at 25 ℃.Ternary phase diagrams of Li<SUB>2</SUB>SO<SUB>4</SUB>-C<SUB>2</SUB>H<SUB>5</SUB>OH-H<SUB>2</SUB>O&nbsp; ternary system at 25 ℃ were plotted.Relations between the saturated solubility of Li<SUB>2</SUB>SO<SUB>4</SUB>,refractive index and density of the saturated solution and the alcohol content in liquid phase were evaluated by multiple linear regression analysis algorithm.Salting-out rate of Li<SUB>2</SUB>SO<SUB>4</SUB> solution against ethanol was calculated.No demixing phenomena were observed and a hydrated salt Li<SUB>2</SUB>SO<SUB>4</SUB>·H<SUB>2</SUB>O was found.A series of phase equilibrium data of Li<SUB>2</SUB>SO<SUB>4</SUB>-C<SUB>2</SUB>H<SUB>5</SUB>OH-H<SUB>2</SUB>O ternary system were given out,which not only provided basic thermodynamic data for solution chemistry,but also provided foundation for purification and extraction of Li<SUB>2</SUB>SO<SUB>4</SUB>.