The heat capacity (C(p)) of solid mixtures of silybin and sodium cholate was measured by a differential scanning calorimeter (DSC). X-ray diffraction and the FT-IR spectroscopy were used to determine the structure of solid mixture. Our results indicate that this binary system is composed of a mixture of two microcrystalline structures. The transformation of heat capacity from silybin to sodium cholate passes through a minimum at w(1) = 0.25, where w(1) is the mass fraction of sodium cholate. Polynomial equations of heat capacity versus temperature and the virial equation of excess heat capacity versus composition were applied to correlate experimental data. The changes of thermodynamic functions of enthalpy, entropy, and Gibbs function were calculated from the data of C(p).