The invention provides a sheet iron electric welding method and belongs to the technical field of welding. The method comprises the following steps that (1) blanking is conducted, specifically, a piece of sheet iron is cut into a required workpiece through a cutting machine, a plate rolling machine is used for conducting rolling forming, the joint between welded junctions is made smooth, and the width of the weld joint is not greater than 1 mm; (2) the angle of the workpiece is adjusted, specifically, the angle between the welded workpiece and the horizontal ground is 30-60 degrees; (3) a common welding machine is adopted, current is adjusted to be minimal, and the temperature is adjusted to be 600-1000 DEG C; (4) a common THJ422 welding rod is adopted; and (5) welding is conducted, specifically, the included angle between the welding rod and the workpiece is 80-100 degrees, and welding is conducted from top to bottom; firstly, a large crator is welded to the vertex; second, the crator is melted into molten iron to flow down by using the welding rod, a soldering clamp is lifted up 1-2 seconds after arc striking of the welding rod, and welding is continued after a pause of 3-4 seconds; and the steps are repeated until welding of the welded junctions of the welded workpiece is completed. The method is applicable to welding of mining machinery, subway tunnels, garbage bins, tool kits and the like. The method is convenient to use, wide in application range, capable of improving the metal welding strength and also beneficial to further development and application of industrial products.