The utility model discloses a magnetic ground wire. A copper bar belongs to the technical field of welding and comprises a copper bar base, two magnets are mounted at the lower end of the copper bar base through two grooves, the upper end face of the copper bar base is connected with a copper movable block capable of rotating in a horizontal friction manner, the movable block is connected with a grounding terminal connected with a grounding connecting wire, and the movable block is further connected with a pull ring convenient for people to operate. The grounding wire clamp can be quickly andtightly connected to a welding piece, and the phenomenon that a grounding wire is bent due to movement in the welding process is avoided.