Abstract: In this paper, the solubilities, viscosities, densities and vapor-liquid equilibrium were studied for the ternary system Li_2SO_4-EtOH-H_2O at 25 ℃. The equilibrium solid phases, which were determined by wet-residue method, were all Li_2SO_4·H_2O in the whole concentration. The solubilities and densities were correlated by using empirical formula In(y/y_0) =K_1x+K_2x~2+K_3x~3 and the good results were obtained. After lithium sulfate was added to the solvent, it was showed that the figure of viscosity, compared with that for the pure solvent system of ethanolwater, make a change because of the action of static electricity of salt ions on the solvent. According to Jaques' pseudobinary model, NRTL and WILSON equations were used to correlate the vapor-liquid equilibrium data of the system. It was obtained that ethanol is a salting out component and water is a salting in component.