Abstract: Described here in the article is a newly developed system for outside/inside surface plastic-coating of medium sized straight pipes longer than 12 m, including spiral and longitudinal welded pipes and seamless steel pipe. Compared with the curtain type plastic-coating system with the investment nearly 100 times higher than it, the new heat-bonding principle-based plastic-coating system for long straight pipe is of simpler structure, but provides functions almost the same as the curtain coating system, being particularly suitable for small and medium operations.