To study the effect of solder process parameters and thermal shock on Sn2.5Ag0.7Cu0.1RE0.05Ni/Cu of soldered joints, the interface intermetallic compounds and strength of the joints were observed and analyzed with the help of SEM, EDS, XRD. The results showed that adding 0.05 wt% Ni can refine the primary β-Sn phase and eutectic of the Sn2.5Ag0.7Cu0.1RE solder alloy. The maximum shear strength was 26.9MPa, which obtained from the joint under the soldering temperature of 270℃ and soldering time of 240s. The maximum shear strength increased 8.9% than Sn2.5Ag0.7Cu0.1RE/Cu joint. The interface roughness, the average thickness of the Sn2.5Ag0.7Cu0.1RE0.05Ni/Cu joint rased with the increasing of temperature and time. The shear strength of the joints increased and then decreased. The interface IMC of the solder joints irregular growth with the rasing of thermal shock cycle. At the same time, the strength of the joint was decreasing. The added 0.05 wt% Ni can inhibite the quick decrease of the reliability of soldered joint in the process of the thermal shock.