Abstract: The influences of the addition Nickel to Sn-3. 0Ag-0.5Cu lead-free solder on the melting point, wettability, tensile properties and the properties of soldering joints were studied.The results show that the solder alloy exhibited improved wettability with the addition of small amount of Nickel.The wetting time decreases gradually and the wetting force increases gradually as Nickel content is within 0.03 %~0.1%.When Nickel content is 0.05% the wetting time is the shortest.When Nickel content is 0.1% the wetting force is the biggest.The solder alloy exhibited very little change on the melting point.The solder alloy of the addition of Nickel exhibited improved elongation percentage and shear strength.When Nickel content is 0.1%, the elongation percentage and shear strength are the highest.Scanning fracture exhibits obvious ductility characteristic.The suitable of addition to the solder Nickel is within 0.05%~0.1%.