An experimental study on phase equilibria at 288 K in the quinary system Li+ + K+ + Cl- + CO32- + B4O72- + H2O was done by the isothermal evaporation method, Equilibrium solubility of the solution was measured, and the equilibrium phase diagram for the solution saturated with salt Li2CO3 was constructed in which there were three invariant points, seven univariant curves, and five crystallization fields corresponding to potassium chloride, lithium chloride monohydrate (LiCl-H2O), potassium borate pentabydrate (K(2)B(4)O(7)center dot 5H(2)O), hydrated lithium borate (Li(2)B(2)O(4)center dot 16H(2)O), hydrated potassium carbonate (K(2)CO(3)center dot 3/2H(2)O). No solid solutions or double salts were found. In comparison with the metastable phase diagram of this quinary system at 288 K and its stable phase diagram at 298 K, the size of the salt crystallization fields and the salt crystallization forms were changed. These changes between phase diagrams at different temperature will be very useful for extracting the salts.