The interfacial interaction between liquid eutectic Sn9Zn solder and electroplated Ni layer was investigated in the temperatures range of 230 ∼ 290°C. The interaction gives rise to various Ni-Zn intermetallic compounds, Ni 5Zn 21 and NiZn 3, and Ni-Zn solid solution layer. The evolution of these layers is temperature dependent. The thickness of the interfacial reaction layer was measured with respect to reaction temperature and reaction time. The growth behavior of the interfacial layer and the activation energy of the interaction were discussed. The reaction mechanism was found to vary with respect to reaction temperature.