The Zr–Cu filler metal is mainly used for the joining of SiC ceramic as a nuclear fuel cladding material. The physical and chemical properties of the alloy, the interfacial reaction between the Zr–Cu filler metal and SiC ceramic, the residual stress of the SiC joint and the thermal neutron absorption cross section of the filler metal are considered during the design of the Zr–Cu filler metal. 80Zr–20Cu (wt%) is used as the filler metal in these experiments, showing good wettability and brazing properties with SiC ceramic.