A manufacturing method of a package carrier is provided. A substrate having a through hole is provided, wherein a profile of the through hole from top view is a first rounded rectangular. A heat conducting slug is disposed inside the through hole, wherein the heat conducting slug and an inner wall of the through hole are separated with a gap, and a profile of the heat conducting slug from top view is a second rounded rectangular. An insulating material is filled in the through hole so as to fix the heat conducting slug in the through hole. A conductive through hole structure, a first and a second patterned circuit layers are formed. The first and the second patterned circuit layers are respectively formed on two opposite sides of the substrate. The conductive through hole structure penetrates the substrate and connects portions of the first and the second patterned circuit layers.