Fusion-bonded polyethylene (PE), ethylene-acrylic acid copolymer (EAA), epoxy (EP) powder, non-toxic polypropylene (PP), or non-toxic polyvinyl chloride (PVC) coatings are applied to the inner surface of steel pipes, creating a steel-plastic composite pipe with a thickness of 0.5 to 1.0mm. This pipe combines the high strength, easy connection, and resistance to water flow impacts of steel pipes, while overcoming their drawbacks such as susceptibility to corrosion, contamination, scaling, and the low strength and poor fire performance of plastic pipes. Its design life can reach 50 years.