Ceramic matrix composites(CMCs) will experience internal damage such as fiber pulling out and matrix cracks during usage, which will affect the mechanical properties of braided CMCs. For SiCf/SiC 2.5-dimensional braided CMCs, a microscopic finite element model of fiber bundle and a meso finite element model of braided CMCs were established, respectively. Considering the randomness of internal damage quantity and location, the probability distributions of mechanical parameters of the meso-scopic level model was identified, and the influence of damage rate on the strength limit and Young"s modulus of the material was studied. Both parametric and non-parametric methods were used to fit the probability distribution of mechanical properties of CMCs. The results show that, with the increase of damage rate, the strength limits decrease faster than the stiffness. In addition, the probability density function curve of strength limit and Young"s modulus obtained by non-parametric method match the frequency histogram of the sample well.