Abstract: OBJECTIVE To calculate the thermodynamic constant of a ternary systerm made up with curcumin, lysine and anhydrous ethanol at different temperatures with different ratio. Moreover, to discuss the rationality of anhydrous ethanol as a specific solvent. METHODS Determine the solubility of curcumin in different concentration of lysine solutions at different temperature, and get the thermodynamic constants by calculating. RESULTS The ternary phase diagrams were graphed; K_sp, K_ll, △G°, △H and △S were calculated. CONCLUSION Anhydrous ethanol could be used as a specific solvent to extract curcumin monomer mixed in curcumin-lysine cocrystal.