In this study, Carbon–Carbon (C–C) composite joints were prepared using BNi-1a paste filler metal as the intermediate layer in a vacuum brazing method. The interfacial structures and compositions of the joints were analyzed using scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and X-ray diffraction (XRD). The results show that element interdiffusion and chemical reactions occurred in the joining zone, and various compounds were formed, including Cr3C2, Ni[Formula: see text]Si[Formula: see text], Ni(s.s), MB and MC ([Formula: see text], Fe, Ni). The optimum joining parameters were determined to be the brazing at the temperature of 1120[Formula: see text]C for 60 min, which produced the joint with the maximum shear strength of 24.13 MPa. The joint shear strength and fracture morphology demonstrate that bonding temperature and retention time have a significant effect on the strength of C–C composites.