A printed circuit board for mobile platforms includes a core substrate having a first side, a ground plane covering on the first side, a first insulating layer covering the ground plane, and a plurality of first signal traces and a plurality of first ground traces, alternatively arranged on the first insulating layer, a second insulating layer connecting to the first insulating layer, and a plurality of second signal traces separated from each other, disposed on the second insulating layer, wherein the second signal traces are disposed directly on spaces between the first signal traces and the first ground traces adjacent thereto, wherein coverage of the ground plane is corresponding to disposition of the first signal trace, the first ground trace, the second signal trace and the second ground trace.