The interfacial reaction of Al2O3 and Ag-Cu-Ti alloy was investigated by scanning electron microscope (SEM) and X-ray diffraction (XRD), respectively. It was shown that Al2O3 ceramic reacted strongly with Ag-Cu-Ti alloy. With the increasing heating temperature and holding time, the reaction layer thickness increased and its growth was mainly controlled by the diffusion of titanium through the reaction layer. The reaction products were Cu2Ti4O and AlTi at or below 1123 K. However, there were two distinct layers at the interface at or above 1173 K, one layer in the vicinity of ceramic consisting mainly of Ti2O and TiO and the other layer near the alloy was CuTi2, a layer transition structures with a Al2O3/Ti2O + TiO/Ti2O + TiO + CuTi2/CuTi2/Ag-Cu formed at the interface according to the SEM and XRD analyses results. A lower or a higher joining temperature and a shorter or a longer holding time were disadvantageous for a stable and high reliable joined interface from the point of view of interfacial microstructures and morphologies.