Based on the free volume theory,lattice model,the Scatchard-Hildebrand theory,novel expressions of configuration partition function and excessive Gibbs free energy and component activity coefficients of solid solutions were developed using configuration partition function and statistical thermodynamics of molecular interaction volume model(MIVM).Herein,the separation of the volume and energy parameters was achieved.The proposed model can reflect the contri-butions from both the molecular configuration micro-state number(entropy)and molecular interactions(enthalpy)toward excessive Gibbs free energy.The proposed equations are more consistent with the practical solid solutions.This model can use either the relevant binary infinite dilution activity coefficients or binary activity to describe and predict the thermo-dynamic properties of the multi-component solid solutions.Applications of the proposed model in some typical binary and ternary solid solution alloys revealed that the thermodynamic properties predicted by the proposed model were consistent with the experimental data and the proposed model was found to be superior to MIVM in terms of the prediction performance.Hence,it can be concluded that the proposed model exhibits good physical basis,applicability,stability and reliability.