The invention provides a circuit board structure for electrical testing and a fabrication method thereof. The circuit board structure includes: a core board having a plurality of first circuits, an electroplating conductive wires, and distributing wires for electrical connection thereof; a dielectric layer formed on the core board, the first circuits, the distributing wires and the electroplating conductive wires, wherein the dielectric layer is formed with at least one opening for exposing the distributing wires; a plurality of second circuit formed on the dielectric layer and electrically connected to the first circuits; a solder mask layer formed on the dielectric layer and the second circuits; and at least one first opening formed in the solder mask layer, above the distributing wires, and deep into the dielectric layer to create a broken circuit between the distributing wires and the electroplating conductive wires, thus enabling electrical testing of the circuit board structure, and reducing noise interference.