The inner and outer plastic-coated steel pipes are made by melting a layer of polyethylene (PE) resin, ethylene-acrylic acid copolymer (EAA), epoxy (EP) powder, and non-toxic polycarbonate with a thickness of 0.5 to 1.0mm on the inner wall of the steel pipe. The steel-plastic composite pipe composed of organic substances such as propylene (PP) or non-toxic polyvinyl chloride (PVC) not only has the advantages of high strength, easy connection, and resistance to water flow, but also overcomes the corrosion of steel pipes when exposed to water. Pollution, scaling, low strength of plastic pipes, poor fire-fighting performance and other shortcomings, the design life can be up to 50 years. The main disadvantage is that it must not be bent during installation. During thermal processing and electric welding cutting, the cutting surface should be painted with the non-toxic normal temperature curing glue provided by the manufacturer to repair the damaged part.