Today we have an understanding of the development of weathering steel abroad. Weathering steel began to be studied in the early 20th century. Weathering steel and Corten steel originated in Europe and America. In 1900, European and American scientists first discovered that Cu can improve the corrosion resistance of steel in the atmosphere. In 1933, U.S. Steel of the United States first developed corrosion-resistant high tensile strength Cu-containing low alloy steel, Corten steel, which was directly applied to buildings and bridges without painting in the 1960s. Among them, the Corten-A series with high Cu, P plus Cr and Ni and the Corten-B series with high Cu, Cr and Mn alloying are widely used. In the 60s and 70s, weathering steel was widely used in Europe and America. The current weathering steels have evolved on the basis of Corten steel, some to increase the strength plus Nb, and some to improve the welding performance drop P plus Mn and so on.