Packaging substrate, forming method thereof and packaging structure

The invention relates to a packaging substrate, a forming method thereof and a packaging structure. The packaging substrate comprises a stacking structure which comprises a plurality of wiring layers which are sequentially stacked along a first direction; the connection structure is located between the adjacent wiring layers in the first direction, the connection structure comprises an interlayer signal transmission structure and an interlayer ground structure, the interlayer signal transmission structure comprises two interlayer signal lines with opposite phases, the interlayer ground structure comprises a plurality of interlayer ground lines which are independent from each other, and the interlayer signal lines are connected with the interlayer ground lines. And the plurality of inter-layer ground wires are annularly arranged around the periphery of the inter-layer signal transmission structure. According to the invention, the parasitic loss of the differential signal during transmission in the packaging su