Abstract: A composite structure includes a first metal layer, a second metal layer, and a ceramic layer disposed therebetween. The ceramic layer has a first surface and a second surface opposite to each other and is adapted to absorb electromagnetic waves. The absorbance reaction range of the electromagnetic waves by the ceramic layer ranges from 100 MHz to 400 GHz. The first metal layer has an opening exposing the second surface. An inner sidewall of the first metal layer surrounds the opening. The orthographic projection of the second metal layer on the ceramic layer at least partially overlaps the orthographic projection of the opening on the ceramic layer. The thickness ratio of the first metal layer to the second metal layer is 1:1 to 1:2. The area ratio of the first metal layer to the second metal layer is 1:1.2 to 1:4. A package architecture including the composite structure is also provided.