Abstract: This paper takes the study of the numerical model and the corresponding algorithm for multi-scale elastic-plastic analysis of composite materials. Main work is focused on the problem of unit cell analysis. A numerical technique with approximation to establish the eigen-strain matrices and the corresponding consistent algorithm are proposed to be easily implemented in the computer program. A numerical example for analysis of a composite material composed of two different materials is computed. Numerical results demonstrate the validity and efficiency of the theoretical work presented in this paper. Finally, some further works are discussed.