Steel-based structures are one of the main types of building structures. Steel is characterized by high strength, light weight, good overall rigidity and strong deformation capacity, so it is especially suitable for the construction of large-span, ultra-high and ultra-heavy buildings. The material has good homogeneity and isotropy and is an ideal elastomer, which is most in line with the basic assumptions of general engineering mechanics. The material has good plasticity and toughness, can have large deformation, and can bear dynamic load well. The construction period is short; it has a high degree of industrialization and can be specialized in production with a high degree of mechanization; it has high processing accuracy, high efficiency, and good airtightness, so it can be used to build gas tanks, oil tanks and transformers. The disadvantage is that the fire resistance and corrosion resistance is poor. It is mainly used for load-bearing skeleton of heavy workshop, plant structure under dynamic load, plate and shell structure, towering TV tower and mast structure, large span structure such as bridge and warehouse, high-rise and super high-rise buildings, etc. Steel structure in the future should study high strength steel, greatly improve its yield point strength; in addition to rolling new varieties of steel, such as H-shaped steel (also known as wide flange steel) and T-shaped steel and profiled steel plate to meet the needs of large span structure and super high-rise building. Steel structure is divided into light steel and heavy steel. There is no uniform standard for judgment, and many experienced designers or project managers often cannot fully explain it. They can comprehensively consider and judge it with some data.