The external anti-corrosion coating of the outer PE inner EP coated steel pipe for drinking water transportation is a single-layer polyethylene coating with external hot melt bonding, and the inner layer is a fusion bonded epoxy resin powder; Hot melt three-layer structure polyethylene coating, the bottom layer is fused epoxy resin powder, the middle layer is hot melt adhesive, and the outer layer is high-density polyethylene. Compared with inner epoxy outer 3PE, polyethylene and epoxy have excellent corrosion resistance, but each has its own advantages.