Abstract: Descaling property of oxide scale of welding wire ER70S-6 was studied by twisting test and by scanning electron microscopy. It was found that, silicon rich layer with iron-silicon oxide Fe₂SiO₄ (2FeO· SiO₂) and FeO as the main component just outside of the matrix is difficult to be eliminated completely by mechanical bending and abrasive belt grinding, and thus to deteriorate copper plating effect and welding performance of the wire product. With measures including impeding diffusion of oxygen into the silicon-rich layer by increasing the temperature of the heating section to 985 ℃;and soaking section to 1110℃  in heating furnace, to promote disproportionation reaction of FeO by establishing the thermal insulation wall and by established thermal insulation corridor around the PF line, to decrease the indentation of oxide scale to the matrix by shortening the roll change time of the finishing mill for 3 h, increasing thickness of oxide scale by reducing the spinning speed to 90 m/s and increasing the spinning temperature to 930 ℃, the effect of mechanical descaling of oxide scale is improved. The peeling form of oxide scale changed from the powder to the lamellar, the intermittent blackening of semi-finished product disappeared, the average thickness of the copper plating layer increased from 1.45μm to 3.6μm, and the surface brightness was significantly improved through the process optimization.