Abstract: In order to study the failure mechanism of the 3D braided SiC/SiC composites, the uniaxial tension and three-point bending tests at room temperature were carried out. Before the experiment, the morphology of the braided structure of the 3D braided SiC/SiC specimen was clarified by means of scanning computed tomography (CT). Microscopic analysis of tensile and three-point bending specimens shows that during the tensile process, the local stress concentrations are developed in the material as a result of the primary pores and microcracks. As the tensile load increasing, the cracks in the transverse direction of the matrix as well as the longitudinal interlaminar cracks between the fiber bundles gradually develop into internal fiber cracks form, ultimately resulting in a brittle fracture of the material. Under the three-point bending load, a combination of shear and tension failure mode is found. The failure firstly happens in the bottom side of the specimen with tensile stress. Then, shear occurrs at the neutral surface. After that, the cracking develops towards both of the top and bottom sides, and finally the 3D braided SiC/SiC specimen fails totally. The fracture surface is strong correlative to the direction of the fiber bundle. The crack propagates substantially along the interface between the fiber bundles, which makes the real failure location different from the theoretical prediction position.