A theory for solvation thermodynamics of binary solution is developed by Virial expansionmethod. The excess energy of binary solution is divided into three interactive terms of solvent - solventsolvent - solute and solute - solute. Using the approach of Virial expansion the partial function of canonicalensemble for a binary solution is expressed. The expression of partial molar energy and entropy of soluteare obtained by this expression. Under the condition of infinite dilution，the solvent - solvent term ofthe excess partial molar energy can also be called as reorganization energy. It shows that the presentationof solute affects interactive energy of solvent molecules around solute molecules. The study in this papershows that when the molar fraction of solute particles is relatively higher，the interaction among solutemolecules would affect the solvent - solvent term of excess partial molar energy. For diluted solution，thesolvent - solvent term of excess partial molar energy is linear to the molar fraction of solute. For binarysolution with low density，the excess partial molar energy and excess partial molar entropy of solute is alsolinear to the density of particles.