Abstract: An electro-thinning apparatus for removing excess metal from the surface metal layer of the substrate is provided. The apparatus includes an electrolysis bath, a transportation system, an anode roller, a cathode roller, and at least one shielding plate. The electrolysis bath contains an electrolysis liquid. The transportation system is disposed in the electrolysis bath for moving a substrate from an upstream end to a downstream end. The anode roller is disposed relative to the electrolysis bath and located upstream to the transportation system. The cathode roller is located above the transportation system and located downstream to the anode roller. The at least one shielding plate is located downstream to the cathode roller. During electrolysis, the anode roller contacts a surface metal layer of the substrate while the cathode roller is partly immersed in the electrolysis liquid and away from the surface metal layer of the substrate during electrolysis.