1. The coating microstructure of reactive thermal spraying of steel-lined tetrafluoroethylene pipeline is a typical thermal spraying layered structure, which has the characteristics of fine structure, roughly spherical hard phase and uniform distribution, and low porosity. 2. The coating preparation cost is low. It is economical. 3. The coating is dense and the bonding strength is high. The reaction heat released by the in-situ synthesis reaction of the steel-lined PTFE pipeline and the flame heat are superimposed, which increases the temperature of the droplet, and can melt, spheroidize and refine the hard phase of the high melting point ceramics, and the distribution is uniform and clean. Improve the bond between metal and ceramic, thereby improving the bond strength between the coating and the substrate, as well as the coating.