Predictive　molecular　thermodynamic　models　can　bridge　the　gap　between　the　microscopic　molecular　level　and　macroscopic　system　scale.　Over　the　past　few　decades,　ionic　liquids　(ILs),　as　a　class　of　green　solvents　and　functional　materials,　have　received　widespread　research　interest　in　the　field　of　chemical　processing　owing　to　their　unique　physicochemical　merits.　This　review　aims　to　provide　an　easy-to-read　and　exhaustive　reference　regarding　state-of-the-art　predictive　thermodynamic　models　for　ILs,　with　more　focuses　on　UNIFAC-　and　COSMO-based　models　and　various　applications　involving　phase　equilibrium　prediction,　guidance　for　IL　screening　and　design,　and　building　equilibrium　stage　models　for　separation　processes.　This　review　provides　a　theoretical　perspective　on　the　structure-property　relationships　between　molecular　structures　and　phase　behaviors　for　the　systems　and　the　constituted　components　covering　a　multi-scale　viewpoint　from　molecular　level　to　industrial　scale.　Moreover,　the　predictive　capacities　of　different　thermodynamic　models　are　comprehensively　compared.