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.