Abstract: A method to predict the strength of 2.5D C/SiC composite was developed, which combined the strength prediction method in micro-scale and FEM model in meso-scale. Strain-stress curve and mechanics properties at the failure point in meso-scale were gotten by calculating the strain-stress curve and mechanics properties at the failure point in micro-scale, diminishing the elastic modulus of elements, and calculating the average strain and stress with different boundary conditions. The tensile propriety was tested at normal and high temperature, meanwhile, the strain-stress curve and mechanics properties at failure point were gotten. The results show that the theoretical results can fit the experimental results well and the theoretical method is validity.