A modified SiC coating was prepared on the surface of C/C composites by a pack cementation process. Ni-Ti mixed powder was used as an interlayer to join SiC coating modified C/C composites and GH3128 Ni-based high-temperature alloy (GH3128) by a vacuum hot-pressing diffusion process. The chemical element distribution, microstructure and mechanical properties of the joint between C/C composites and GH3128 were investigated by X-ray diffractometry, scanning electron microscopy, energy-dispersive spectrometry and material universal testing machine. Results show that the SiC modified coating on the surface of C/C composites not only improves fully the wettability of C/C composites to the Ni-Ti intermediate layer, but also alleviates effectively the thermal stress in the joint due to mismatch thermal expansion. Under the same joining condition, the shear strength of the joint with SiC modified coating at room temperature is up to 22.50 MPa, whereas that of the joint without SiC coating modification is almost 0.