According to the partial homogenization and total homogenization features of the CO₂-H₂O system during heating process, the authors establish a thermodynamic model based on the latest thermodynamic parameters and related models. The molar volumes of the same one fluid inclusion are nearly same in partial homogenization state and total homogenization state. A new software based on this method is developed, which can be applied to the CO₂-H₂O system at T<623.15 K, P<100 MPa with total homogenization to liquid phase or critical phase. Comparative studies show that the software can also be extended to low salinity (<6%) CO₂-H₂O system within a relative error of 10%.