Abstract: Elaborated in the article is the innovative design and relevant practice by a domestic company for building an environment-friendly and energy-saving plant under a Φ159 mm seamless steel tube mill project. The design involves lots of new technologies, new equipment and new material, etc. Focused on here are the innovative design ideas, and energy-saving/emission-reducing techniques and measures as taken into considerations when designing such aspects as rolling process equipment, heating furnace, water supply-drainage system, electrical drive system, ventilating and dedusting system, air-conditioning devices and workshop buildings, etc. The operation for two years since the start up of the new mill under the said project shows that all the actual indexes of the mill have met the design requirements, while the designed objectives concerning energy-saving, emission-reducing and comprehensive utilization of surplus energy and wastes as well as improvement on production conditions have been all realized, too.