A molecular thermodynamic model based on the theory of melting point depression, the Adam-Gibbs configurational entropy model, and the lattice fluid model was developed to interpret the ionic conductivities of solid polymer electrolytes with various pressures. Quantitative descriptions according to the proposed model are in good agreement with the experimental data for the given systems. Our results show that an eutectic point moves toward a higher T-m and lower weight fraction of salt, and the ionic conductivity significantly decreases with pressure.