Abstract:C/C composites are the important structure materials for aerospace and nuclear applications. Realizing the joining of C/C composite to metal materials can overcome the drawbacks of high cost and hard-to-forming difficulties of C/C composite. In this paper, C/C composite and Invar alloy were brazed with active Cu-Sn-Ti filler alloy. The effects of brazing temperature and holding time on the microstructure, shear strength and fracture behavior of brazed joints were investigated. The results showed that, on the side of C/C composite, Cu-Sn-Ti filler reacted with C/C composite to form a TiC reaction layer. In addition, Cu-Sn-Ti filler would penetrate into the C/C composite, which formed a zigzag interface that strengthened the joint. On the side of Invar alloy, Invar alloy dissolved into Cu-Sn-Ti form a good interface metallurgical bonding. The interfacial microstructure of brazed joint was determined to be Invar alloy/Cu(s,s)+Fe2Ti+Ni3Ti+Ti6Sn5/Fe2Ti+CuTi+Cu3Sn/TiC+Cu(s,s)/C/C composite. The maximum shear strength of the joint of 61 MPa, which is significantly higher than the strength reported in previous studies, was obtained at brazing temperature of 930 ℃ and the holding time was 10 min.