The invention discloses brazing filler metal and a process for brazing molybdenum-rhenium alloy. The brazing filler metal comprises, by weight, 7-15% of Mn, 3-6% of Co, 0-8% of Zr and the balance Cu. A method for preparing the brazing filler metal includes proportionally uniformly mixing the Cu, the Mn, the Co and the Zr with one another to obtain mixtures; preparing the brazing filler metal in the shape of a foil strap by the aid of a vacuum induction smelting furnace and a high-vacuum melt-spinning machine. The thickness of the brazing filler metal ranges from 20 micrometers to 50 micrometers. The brazing filler metal and the process have the advantages that the brazing temperature of the brazing filler metal ranges from 1020 DEG C to 1090 DEG C, the brazing filler metal has an appropriate melting temperature, the high-temperature performance of the brazing filler metal can be guaranteed, and the brazing filler metal can be uniformly molten; brazing filler metal foils are favorable for promoting diffusion and interface reaction of alloy elements in brazing connection procedures, the wetting and spreading capacity of the brazing filler metal on the surfaces of the molybdenum-rhenium alloy can be improved, crystalline grains can be refined, residual stress can be reduced, and the mechanical properties of connectors can be improved.