The working principle of the steel-faced magnesium fire and smoke exhaust composite duct is achieved through its fire-resistant and insulating layer, which combines fire resistance, heat resistance, and insulation. This prevents the spread of fire during a fire by blocking air flow. The ducts are made with protective steel surfaces or both inner and outer protective layers, using high-corrosion-resistant metal plates or corrosion-resistant aluminum foil, with a service life of over 30 years. The duct connection materials use special angle steel flanges, featuring high connection strength and easy installation. Moreover, the steel-faced magnesium composite duct material is a laminated plate made from steel base materials processed through cold rolling, hot rolling, and other processes, combined with magnesium-based composite materials that excel in high-temperature wear and corrosion resistance. The surface is coated with a layer of glass fiber reinforced epoxy渗透resin that has insulating and corrosion-resistant properties, applied through a high-temperature spraying technique, followed by a layer of high-temperature wear-resistant magnesium铝合金 material, providing excellent strength, wear resistance, corrosion resistance, and insulation properties.