The RbCl-ZnCl2 and CsCl-ZnCl2 binary systems with different proportions are firstly prepared to determine the phase equilibrium relation using differential scanning calorimetry (DSC) and X-ray diffraction (XRD) methods. The phase diagrams of RbCl-ZnCl2, CsCl-ZnCl2 and RbCl-CsCl are thus critically optimized by thermodynamic modeling based on the available experimental values. The associate solution model (ASM) is used to describe the liquid phases of RbCl-ZnCl2 and CsCl-ZnCl2 binary system, and the substitutional solution model (SSM) is applied for the RbCl-CsCl binary system. All Gibbs energies of intermediate compounds are treated with the Neumann-Kopp rule. In light of this, a set of self-consistent thermodynamic database is obtained and applied to predict the thermodynamic properties of the RbCl-CsCl-ZnCl2 ternary system by merging the Gibbs energies in its subsystems via the Kohler-Toop interpolation method. These results could provide effective data supporting for the selection and optimization of multi-component molten salts for the concentrating solar power (CSP) plants. (C) 2019 Elsevier B.V. All rights reserved.