Several different perturbation terms were extended to copolymer mixtures. Based on Hu et al.'s equation of state for heteronuclear hard-sphere chain fluids, four versions of equations of state for copolymer mixtures are proposed. The selected perturbation terms include Cotterman-Schwarz-Prausnitz (CSP) model, O'Lenick-Chiew (O'LC) model, Gross-Sadowski (GS) model, and Chen-Kreglewski (CK) model. Model parameters of equation of state can be obtained by fitting pVT data of pure polymers. The proposed equations were tested with the correlation of the specific volumes of pure copolymers and blends and the prediction of the specific volumes for copolymers and blends. It was found that those equations of state could give a better correlation with one adjustable parameter or prediction.