In this work, a calculation model of CO2 solubility in equilibrium with hydrate was developed on the basis of the Patel-Teja equation of state and Chen-Guo hydrate model. The solubility of CO2 in water and NaCl solution in equilibrium with hydrate were calculated respectively under the temperature window of 273.95 K to 282.55 K and the pressure window of 2.0 MPa to 8.0 MPa. The comparisons between the calculated and experimental values show that the average absolute deviation percentages (AADP) are 2.12 % for the CO2/H2O system and 2.31 % for the CO2/ NaCl/H2O system, respectively. It demonstrates that the model proposed in this work could well predict the solubility of CO2 in NaCl solution in equilibrium with hydrate.