Abstract: In-situ tensile experiments of 2D SiC/SiC composites were carried out to reveal the influence law of applied load on the crack evolution characteristics of the materials. The experimental results show that under uniaxial tensile loading, the crack density and crack width of 2D SiC/SiC composites show significant load correlation. The crack density evolution is mainly regulated by the degree of interfacial debonding. When the degree of interfacial debonding is low, the stress transfer efficiency increases and the matrix is prone to nascent cracks. By establishing a Weibull distribution model to describe crack density, the average absolute error and root mean square error are 0.053 and 0.077, respectively, compared with in-situ test data. Accurate description of the relationship between crack density and stress has been achieved. Crack width extension, on the other hand, is closely related to stress and interfacial shear stress. The crack width-stress ontology model was constructed to successfully reproduce the evolution trend of crack width at different loading stages. This study provides a new analytical method and theoretical basis for the multi-scale damage characterization of ceramic matrix composites.