In-situ formed interfacial carbides always sacrifice the structure integrity of reinforcement in nanocarbon/metal composites. Herein, leaf-like carbon nanotube-graphene nanoribbon (CNT-GNR) hybrids, consisting of CNT midrib and GNR margin, was synthetized to solve the above dilemma in nanocarbon-CuCr system. Results demonstrate that high-density nano-sized Cr7C3, which had specific orientation relationship related to the CuCr matrix ([0 0 1]Cr7C3//[011]CuCr, (2‾ 20) Cr7C3//(11 1‾)CuCr), was in-situ formed at GNR-Cu interface via “heterogeneous nucleation-growth” pattern. Meanwhile, the integrity of CNT midrib was well-retained. In-situ SEM tensile results show that such designed interface effectively prevents crack propagation, makes crack blunt via coordinated plastic deformation of local matrix, and guarantees the failure of CNT-GNR by breakage mode, being crucial for exerting the toughening and promoting strength-ductility synergy of CNT-GNR/CuCr.