The separation of phenanthrene (PHE) and carbazole (CAR) has been a tough job since the formation of solid solutions. Development of new separation strategy for PHE-CAR mixture highly depends on their phase equilibrium behaviour. In this work, ternary phase diagrams of phenanthrene (PHE) and carbazole (CAR) in dimethylformamide (DMF), acetone, acetonitrile (MeCN) and toluene at T = 308.15 K under normal atmosphere were determined through wet residue method. It was found that PHE-rich solid solution a was formed in the particular composition range of PHE-end. On the contrary, no CAR-rich solid solution was formed in CAR-end. These results were further verified through powder X-ray diffraction (PXRD) and differential scanning calorimetry (DSC). Based on the ternary phase diagrams, a difference coefficient of solubility (Ds) was put forward to assist screening and evaluation of solvents for solution crystallization. Among the four tested solvents, toluene is the most suitable one for separating PHE-CAR mixture. (C) 2018 Elsevier Ltd.