A semiconductor package substrate and a method for fabricating the same are proposed. An insulating layer has a plurality of blind vias to expose inner traces underneath the insulating layer. A conductive film is formed on the insulating layer and over the bind vias. A first resist is formed on the conductive film, having openings to expose parts of the conductive film. A patterned trace layer including a plurality of contact pads is formed in the openings and the blind vias to form conductive vias, with at least one contact pad electrically connected to one conductive via. A second resist is formed on the patterned trace layer without covering the contact pads. A metal barrier layer is formed on the contact pads. Finally, the first and second resists and parts of the conductive film covered the first resist are removed.