Abstract: On the basis of two-fluid polymer coordination solution model, an equation of state (EOS) for polymer mixtures is derived, and applied to pVT correlation of four polymer mixture systems (polyisobutene/cyclohexane,polyisobutene/benzene, polydimediylsiloxane/hexadimethyl-siloxane, polydimethyl siloxane/benzene). A satisfactory accuracy is obtained. A new concept named fluidity coefficient is proposed. It could be obtained from equilibrium properties (pVT data),and used to predict the transfer properties.