Abstract: The wetting match properties of Sn2.5Ag0.7Cu0.1RE lead-free solder on the surface of copper wire with tiny Ni addition and different soldering parameters by adopting commercial water-soluble flux were investigated by means of wetting balance methods. The obtained results show that the microstructure of Sn2.5Ag0.7Cu0.1RExNi solder alloy can be refined with the addition of 0.05 % Ni; and it has better wetting match proprieties on the surface of 0.6×30 mm copper wire at soldering temperature of 255 ℃, soldering time of 5 s, impregnating speed of 20 mm/s and the impregnating depth of 3 mm, i.e. it has higher wetting force, smaller wetting angle and shorter wetting time. The wetting properties can fully accord with the standards of the wetting force, wetting time and wetting angle, and meet the standard to the lead-free solders of surface mount technology industry.