Abstract: In order to solve the problems such as poor structural integrity, inhomogeneous dispersion and agglomeration of graphene in the brazing seam, PECVD process was utilized for in-situ preparation of high-quality graphene-coated Cu foam composite interlayer prior to being applied to braze C/C composite and Nb. Raman, SEM, HRTEM tests were carried out to characterize the prepared graphene and the brazed joints. The results show that graphene acquired even distribution in the brazing seam with the help of Cu foam, which owned interconnected porosity. Simultaneously, the excellent chemical inertia of graphene inhibited the collapse of Cu foam. Furthermore, based on the synergistic reinforcement effect of Cu foam, with good plastic deformation capacity, and graphene, with extremely low coefficient of linear expansion, the thermal residual stress in the joint has been effectively mitigated. The average shear strength of the joint was evidently improved.