Abstract: To investigate the effects of fiber directionality and interface types on the tensile properties, 3D 4-directional and 3D 5-directional braided SiC/SiC composites were prepared by polymer infiltration and pyrolysis (PIP) process, and combined interface of PyC/SiC composite was introduced to the braided SiC preform surface for modification. The results indicate that 3D 5-directional SiC/SiC composite shows great advantages in tensile properties over 3D 4-directional SiC/SiC composite. The tensile strength, modulus and fracture strain of 3D 5-directional SiC/SiC composite are respectively 1.22 times, 1.25 times and 1.43 times of the corresponding properties of the 3D 4-directional SiC/SiC composite. Furthermore, 3D 5-directional SiC/SiC composites have better strength reliability than that of 3D 4-directional SiC/SiC composite. This is due to the increase of fiber content in the stress direction of the 3D 5-directional SiC/SiC composites, which limits the rotation and deformation of the fiber under the external force, resulting in shaping and stabilizing. With the interface of PyC/SiC, the tensile strength, tensile modulus and fracture strain of 3D 5-directional SiC/SiC composite increase by 21.7%, 15.0% and 11.0%, respectively. The interface can protect the fiber and adjust the thermal stress between the fiber and the matrix, which can induce the deflection and bifurcation of cracks and consume energy, resulting in the improvement of tensile properties of the 3D 5-directional SiC/SiC composites.