Abstract: A signal transmission structure suitable for a multi-layer circuit substrate comprising a core layer and at least a dielectric layer is provided. The signal transmission structure according to the present invention comprises a first via landing pad and a reference plane. The first via landing pad is disposed on a first surface of the core layer, and covering one end of the through hole of the core layer. The dielectric layer covers the first via landing pad and the first surface of the core layer. And the first reference plane is disposed above the dielectric layer, having a first opening disposed above one end of the through hole. Wherein, the area where the first reference plane is projected on the first surface of the core layer does not overlap with the area where the first via landing pad is projected on the first surface of the core layer.