A printed circuit board includes a reference layer configured to connect to a power or a ground and a dielectric layer stacked on the reference layer. The dielectric layer includes a component surface opposing the reference layer. The component surface forms a differential pairs, a protection runner, and a power runner. The differential pairs include a substantially linear part. The protection runner is intervened between the linear part and the power runner, and is substantially parallel to the differential pairs. The length of the protection runner is approximately equal to that of the linear part. Each of the two ends of the protection runner forms a via that electrically connects the protection runner to the reference layer.