The binodal curves of the aqueous two-phase system (ATPS) containing polyoxyethylene (10) lauryl ether (POELE10, C32H66O11) and three tartrate salts ((NH4)(2)C4H4O6, K2C4H4O6, and Na2C4H4O6) were determined at the temperatures (288.15, 298.15, and 308.15) K. The binodal data in the studied systems were fit by three known equations, and a satisfactory correlation effect was obtained. The liquid liquid equilibrium (LLE) data for the investigated systems were calculated by computer software in terms of the lever rule and correlated by the Othmer-Tobias and Bancroft equations, respectively. The salting-out ability of salt was discussed from two different perspectives: anion and cation. The analysis on the Gibbs free energy of hydration of the ions and the binodal curves found that the salting-out ability of salt strengthened with the increase in absolute value of the Gibbs free energy of anion (cation) when the salt consisted of the same cation (or anion). The order of salting-out ability of salts with the same cation was KOH < K2C4H4O6 < K2CO3 < K2HPO4 < K3PO4, and the order of salting-out ability of salts with the same anion (NH4)(2)HPO4 < K2HPO4 and (NH4)(2)C4H4O6 < K2C4H4O6 < Na2C4H4O6. The effect of temperature on the phase diagram of ATPS was studied. It was found that it is favorable to form the ATPS when the temperature rises and that the absolute value of the slope of the tie-line (STL) increased with the rising temperature. In the investigated systems, the effective excluded volume (EEV) is calculated at the different temperatures, and it was found that the greater value of EEV of the systems corresponds to the stronger phase formation of the ATPS.