The reactions between Cu and the eutectic SnBi (Sn58wt.%Bi) solder alloy with and without 1wt.%Ni addition were investigated in this paper. After as-reflowed process, the IMCs formed in the Sn58wt.%Bi/Cu and Sn58wt.%Bi1wt.%Ni/Cu joints were Cu6Sn5 and (CuNi)6Sn5, respectively. During aging process, the thickness of the IMC layers formed at each solder/Cu joint increased, and a new layer Cu3Sn formed adjacent to the Cu substrate. It was found that 1wt.%Ni addition in Sn58wt.%Bi solder alloy could slightly enhance the growth rate of the total IMC layer, but effectively reduce the growth rate of Cu3Sn layer during aging process. The growth behavior of IMC layer for each joint followed the diffusion-controlled mechanism during aging.