The use of ionic liquids as green and biocompatible solvents has many advantages over the use of traditional organic solvents in the liquid-liquid extraction process. Aqueous biphasic systems (ATPS) are an effective method for the separation and purification of proteins, membranes, enzymes, viruses and biological products, antibiotics and are also used in the separation of precious metal ions and drug molecules. In this study, the fuzzy behavior in a two-phase aqueous system including water components, 1-hexyl-3-methylimidazolium methyl sulfate [Hmim][mSO4] in the presence of Na2CO3,K2CO3 and K3PO4 at three temperatures 298.15 K, 310.15 K, 320.15 K was evaluated using the equilibrium point method. also, the interface lines related to all two-phase systems in three temperatures of 298.15, 310.15, 320.15 at atmospheric pressure and calculations related to the length of the interface lines and their slope were calculated and the effect of temperature was evaluated. Based on the results presented in this study, decreasing the temperature increased the biphasic region. Then the isolation of the biological compound BSA with the mentioned two-phase aqueous system in the presence of salt was studied. In this study, the effect of temperature, initial concentration of ionic liquid, type and initial concentration of salt, initial protein concentration and pH on bovine serum albumin protein distribution was investigated. The results show that in addition to desalination effects, other factors such as Hydrophobic forces and electrostatic interactions had the greatest effect on the protein distribution coefficient and had a better performance at ambient temperature. Keywords Liquid-liquid equilibrium, extraction, protein ,BSA , ionic liquids, Aqueous two-phase system