The utility model relates to a large-diameter carbon dioxide protecting welding wire which is suitable for welding various metal and alloy materials. A plurality of fine solid welding wires are combined into a whole and then are processed into a large-diameter welding wire through a protecting layer with an anti-oxygenizing surface. The diameter of the large-diameter welding wire is more than 2.6mm and can be curled into a disc shape, and the diameter of the welding wire can be arbitrarily enlarged according to the actual requirements of sites. The large-diameter carbon dioxide protecting welding wire not only can be arbitrarily bent, but also can not be affected by the diameter size of the welding wire so as to meet the requirements of different welding seams, and can be once stacked and formed without multi-time and repeated stacked welding, and the power consumption is saved from 50 percent to 60 percent. The utility model has the advantages of high work efficiency, labor and time saving, good effect, safety, reliability, stable performance, convenient use, wide practicality and no disc explosion, and is a new substitute of a dioxide gas protecting welding wire.