The intermediate compounds, K3DyCl6, K2DyCl5 and KDy2Cl7, in the DyCl3-KCl system, are confirmed by X-ray powder diffraction method. With CALPHAD technology the phase diagram of the DyCl3-KCl system is re-optimized and calculated using ChemSage software. A set of thermodynamic functions has been optimized based on an interactive computer-assisted analysis. The calculated phase diagram and optimized thermodynamic parameters are thermodynamically self-consistent.