This disclosure provides a package substrate and its fabrication method. The package substrate comprises: a first dielectric material layer have an opening; a first conductive unit including a first part in the opening of the first dielectric material layer and a second part on the first dielectric material layer; and a second dielectric material layer covering the first conductive unit and the first dielectric material layer; wherein a height of the first conductive unit is larger than a thickness of the first dielectric material layer; wherein a cross-section of the second part is larger than that of the first part in the first conductive unit.