Palladium-free Nickel coating was deposited on the surface of carbon fibers by electroless plating method. Nickel coated carbon fibers reinforced Sn-3.0Ag-0.5Cu composite solder was made using the powder metallurgy technique. Microstructure of composite solder was observed and analyzed with the help of SEM, EDS and OM. The effect of Nickel coated carbon fibers contents on the microstructure and properties of composites solder was studied. The results showed that nickel plated carbon fiber was mainly distributed in the grain boundary of the composite solder. The dispersity of coated carbon fiber decreased with its content increasing, while the melting point of composite solder changed little. When the coated carbon fiber content was greater than 1wt%, the reinforced phase appeared obvious agglomeration, which led to the higher electrical resistivity. The added 1wt% coated carbon fiber will be helpful to decrease the surface tension of liquid composite solder between the flux and Copper substrate, which caused the excellent wetting effect. At the same time, the current density of solder matrix was decreased, which resulted in the lower electrical resistivity of composite solder.