The invention relates to a welding gun for the butt welding of flat type copper wires, belonging to the technical field of transformer tools and equipment and comprising an insulated handle (1), a control button (2), lead copper plates (3), copper leads (4), copper pipes (5) and carbon rods (6), wherein the double-row lead copper plates are fixed on the insulated handle through bolts and nuts; the copper pipes are welded on the front end of each copper plate; the carbon rods are inserted into the copper pipes and fastened from the side through screws; the two carbon rods are parallelly arranged side by side; the control button is arranged on the insulated handle; the control button controls an electromagnetic switch arranged on a copper welding machine through leads to switch on and off the copper welding machine; and the copper leads are connected with the copper rows. The invention has the advantages of simple structure and convenient operation; the wires are heated in a single facemode; the butt welding can be carried out after finishing winding; and with respect to the welding of transposition wires, the shape, the size and the welding quality can be easily guaranteed.