Abstract: The isothermal vapor-liquid equilibrium data for carbon dioxide-dimethyl ether-methanolwater quter-nary system were measured at 298.15,313.15,333.15,353.15 K in a self-sucking type agited static equilibrium cell. The pressure of cell was recorded using an on-line computer and acquisition system. The composition of vapor phase and liquid phase were analysed using gas chromatography. Thermodynamic calculation of vapor-liquid equilibrium data for carbon dioxide-dimethyl ether-methanol-water quternary system were carried out using method based on equation of state-activity coefficient, PR equation for fugacity coefficient of gas phase and NRTL equation for activity coefficient of liquid phase. The calculated data fit the experimental data well.