Solubilities, densities and refractive indices of the aqueous quaternary system of lithium sulfate, lithium metaborate, and lithium carbonate at 288.15, 298.15, 308.15 K and 0.1 MPa were determined with isothermal dissolution method. According to the experimental results, the dry-salt phase diagrams, water-phase diagrams, and the diagrams of physicochemical properties including density, pH, and refractive index versus composition of lithium sulfate at three temperatures were plotted. In the dry-salt phase diagrams at three temperatures, there are four crystallization regions corresponding to lithium metaborate octahydrate (LiBO2 center dot 8H(2)O, LB), lithium carbonate (Li2CO3, LC), and lithium sulfate monohydrate (Li2SO4 center dot H2O, LS), and three univariant-solubility curves corresponding to minerals of LS, LB, and LC, and one invariant point of three coexisted minerals (LS + LB + LC). A comparison of the phase diagrams at 288.15, 298.15, and 308.15 K shows that the areas of lithium sulfate monohydrate and lithium metaborate octahydrate are decreased obviously and the area of lithium carbonate region is increased significantly with the increase of temperature from 288.15 to 308.15 K Physicochemical properties of density and refractive index in the quaternary system change regularly with the increase of temperature and the dry-salt composition of Li2SO4 (g/100 g.S) in the solution. With the increase of Li2SO4 (g/100 g.S) in the solution, density and refractive index are increased first to reach the maximum values at the invariant points of three coexisted minerals and then decreased sharply. The calculated values of densities and refractive indices in the quaternary system at three temperatures with the empirical equations are in good agreement with the experimental values.