A semiconductor package includes a first sub-package and a second sub-package. The first sub-package is stacked atop the second sub-package. Each of the first sub-package and the second sub-package includes at least two first semiconductor dies, a second semiconductor die, a plurality of molding pieces, a bond-pad layer, a plurality of redistribution layers (RDLs) and a plurality of bumps. The bumps of the first sub-package are attached to the bond-pad layer of the second sub-package.