Comprises of plastic layer, binding layer and steel tube. The binding layer between the plastic layer and steel tube binds these two layers in a seamless connection through special technique. The biggest advantage is that it solves the problem of insufficient corrosion resistance in the pressure steel tube as well as insufficient pressure resistance in the corrosion resistance plastic tube. The tube ends are sealed to isolate the internal wall from air and moisture so that the steel tube is not subject to rusting, which makes sure the tube service life is up to 10 years under normal condition. It features aging resistance, high intensity, rust-free, odor-free, toxic-free , low cost and easy to install. It is the ideal tube for greenhouse, telecom engineering, operation platform and various of brackets.