In view of the lower boiling point of acetone and no acetone/water azeotrope, it is a significant work to study the liquid-liquid phase equilibria for acetone + water + high-solubility inorganic electrolyte system. K4P2O7 was superior to K2CO3, K2HPO4, and K3PO4 in the separation of acetone from the aqueous solution. Both 600 g/kg of K2HPO4 and 550 g/kg of K4P2O7 drove the acetone recovery high into even 100.00%. When the initial concentration of K4P2O7 was equal or greater than 400 g/kg, the desalination of the organic phase was satisfied. More than 96% of water from the aqueous acetone solution was removed. The reported efficient aqueous twophase system can be applied to recover acetoin and biobutanol from fermentation broths efficiently.