Abstract: To construct a thermally matched joint between C/C composites and AlN ceramics, active brazing joining of the two materials was achieved using an AgCuTi + SiC composite brazing filler metal. The influence mechanism of SiC addition content on the interfacial microstructure and mechanical properties was studied, and the interfacial reaction and stress relief mechanisms were analyzed. The typical microstructure of the brazed joint was C/C composite/TiC/Ag(s, s) + Cu(s, s) + Ti₃SiC₂ + Ti₅Si₃ + TiC/TiN/AlN. The shear strength of the joints showed a variation mechanism that it first increased and then decreased with the increase of the SiC second phase content. When the SiC addition content was 3% (mass fraction), and the brazing process parameters were 820 ℃/15 min, the shear strength reached a maximum value of 27 MPa. The results indicate that the introduction of SiC reinforcing phases can regulate the coefficient of thermal expansion of the brazing filler metal, form a gradient transition between the brazing seam and the base materials, and effectively relieve the large residual stress caused by the mismatch of the coefficient of thermal expansion between the central region of the brazing seam and the base materials on both sides, thereby improving the strength of joints.