Abstract: In protective atmosphere furnace, mono-crystalline diamond was brazed with Ni-Cr alloy, the morphology of the carbide formed on the surface of diamond, fracture appearance and microstructures of the brazed seam were analyzed with scanning electron microscope and XRD.The results show that the diamond brazed in protective atmosphere furnace can realize high strength bonding.The brazed diamond has distinct edge and intact morphology.On the surface of the diamond, the arrangement of Cr₃C₂ is regular, the growth directions take on certain orientation relationship with the(111) crystal planes of diamond.All of Cr₇C₃ nucleate and grow on the surface of Cr₃C₂.Finally, the exothecium Cr₇C₃ and regular arrangement endothecium Cr₃C₂ were formed.