Abstract: Previous molecular thermodynamic model based on the statistical theory of chemical association for pure homonuclear hard-sphere chain fluids has been extended to the mixture of heteronuclear hard-sphere chain fluids. Good agreement can be obtained by this model without any adjustable parameters compared with computer simulation results of the comprcssibility factors of heteronuclear hard-sphere chain fluids and their mixtures. The generalization presented here can be used to the mixtures of heteronuclear hard-sphere chain molecules differing among themselves in both the chain length and diameter of sphere segments. The model can be used as the basis of the molecular thermodynamic model for real polymer solution,polymer blend and copolymer systems.