A semiconductor package includes a first die structure, a first redistribution structure that is disposed on the first die structure, a second die structure that is disposed on the first redistribution structure, and a second redistribution structure that is disposed on the second die structure. The first die structure includes an interposer, and the interposer includes a semiconductor substrate and through-vias that penetrate through the semiconductor substrate. A first integrated circuit die is disposed in the semiconductor substrate of the interposer. The second die structure includes a second integrated circuit die that is encapsulated in an encapsulant and several conductive pillars that penetrate through the encapsulant. The first integrated circuit die is electrically connected to the second integrated circuit die through the first redistribution structure, the conductive pillars, and the second redistribution structure.