Steel-plastic composite pipe is the tube stock with welded steel pipe as the middle layer, inside and outside epoxy coated with a heavy-duty plastic, using special adhesives, composites by extrusion molding method into one. It has a relatively high pressure, impact resistance and other characteristics than plastic pipe. Inner and outer layers plastic of steel-plastic composite pipe has played a role in anti-corrosion, with a smooth wall, resistance to chemical corrosion, no pollution, fluid resistance, no scaling, no microbial growth, the fluid without secondary pollution. Steel-plastic composite pipe overcome the defects which steel pipe have like easy corrosion, contamination, bulky, short life, and the presence of low strength plastic pipe, the expansion capacity, easy deformation of, but meanwhile with steel and plastic pipes' common advantages, such as every oxygen is good, with high rigidity and high strength, easy detection of buried pipe.