Several models used for describing the Gibbs energy of liquid phase containing rare earth chlorides are briefly discussed. In order to reliably predict the ternary thermodynamic properties from its sub-binary ones, a thermodynamic criterion is proposed to reasonably identify the symmetry of ternary system. A series of binary and ternary phase diagrams of the rare earth containing chloride systems have been optimized and calculated. The agreement between calculated and measured phase diagrams is good enough. Several models used for describing the Gibbs energy of liquid phase containing rare earth chlorides are briefly studied. series of binary and ternary phase diagrams of the rare earth containing chloride systems have been optimized and calculated. The agreement between calculated and measured phase diagrams is good enough.