The present disclosure provides a method of manufacturing a semiconductor package assembly. The method includes steps of providing a plurality of first dies arranged horizontally; forming a redistribution layer on the first dies and the first insulative material, wherein the redistribution layer is divided into a first segment and a second segment electrically isolated from the first segment; mounting a plurality of second dies on the first segment of the redistribution layer; depositing a second insulative layer on the second dies and the redistribution layer; and forming a plurality of conductive plugs penetrating through the second insulative material and contacting the second segment of the redistribution layer.