Abstract: A method of coupling a pseudo-binary model with equation of state was presented for the calculation of the gas-liquid equilibrium(GLE)data of a CO2-CnAlCl4(C6H5CH3)n system at elevated pressure. The apparent critical parameters and the apparent eccentric factors obtained by the pseudo-unitary model were used as characteristic parameters of these non-aqueous salt-containing solutions. Regressions of two adjustable parameters of P-R EOS were obtained by the experimental GLE data. Taking the effect of the mixing rule on the accuracy of calculation into consideration, it was found that the P-R equation was greatly improved by employing the modified mixing rule. Results obtained showed that the pseudo-binary model coupled with the EOS method could be used for the GLE of the type of system under study.