The effect of carbon fibers (Cf) and Ni nanoparticles addition on the melting point, microstructure, shear strength, indentation hardness and indentation creep of SnBi
58
/Cu solder joints were explored. Composite solder with various Cf percentages (0, 0.02, 0.04 and 0.06 wt.%) and 0.1 wt.% Ni nanoparticles were prepared by solder paste stirring method. The results indicated that the adulteration of Cf and Ni nanoparticles refines the microstructure and improves the mechanical properties of Sn58Bi (SnBi
58
)/Cu solder joints. However, the added materials have a relatively small impact on the melting point of the composite solder. Solder joints containing 0.04wt.% Cf and 0.1 wt.% Ni nanoparticles showed the best performance in all samples. Compared with SnBi
58
/Cu solder joints, the shear strength and indentation hardness of SnBi
58
-0.1Ni-0.04Cf/Cu solder joints was increased by 28.35% and 16.84%, respectively. Furthermore, the indentation creep decreased by 19.61%. When the addition of 0.06 wt.% Cf, there were more voids and Cf accumulation in SnBi
58
-0.1Ni-0.06Cf/Cu solder joints, which resulting in the shear strength and indentation hardness of SnBi
58
-0.1Ni-0.06Cf/Cu solder joints were reduced.