Abstract: A finite element model of C/C-SiC microstructure characterizing different scale parameters was established for the woven C/C-SiC composites. The strain energy method was used to study the effects of relevant parameters of the microstructure on the macroscopic performances of C/C-SiC composites. The numerical computing results were compared for many cases of C/C-SiC composites with different scale parameters. It is shown that the elastic properties of C/C-SiC composites are associated with the scale parameters identified in the C/C-SiC composites. The effective moduli agree reasonably with the experimental ones. 