In practical applications, C/C composites often need to be joined to metals. However, one major issue that needs to be addressed is the high residual stress in heterogeneous joints. To enhance the interfacial bonding between C/C composites and metals, this study has utilized ultrafast high-temperature shock (UHS) to selectively oxide C/C composites, resulting in the formation of a zig-zag microstructure on the surface. By achieving an extremely short processing time of only 30 s, the efficiency of oxidation process has been improved by several hundred times, leading to a reduction in the rate of weight loss to less than 3%. After brazing, the filler penetration zone is formed, which effectively increases the bonding area between filler and C/C composites, improves pinning effect and alleviates residual stress. Notably, the joints demonstrate a shear strength of 25.3 MPa, which is 1.9 times higher compared to the original joints without employing oxidation process.