The Zunhua iron works was the last state monopoly iron industry in Imperial China. Its history could be a clue to explain why such a well-developed iron industry in ancient China faded after the works collapse. From the available historical record, the study found that the iron works had a complex history with several openings, closings and relocations. In order to prove this, field investigations were carried out and three locations were finally confirmed, and a well-preserved furnace and many iron- and steel-making relics were found. Lastly, these relics, including the fuel, iron ores, and flux, were analyzed in order to infer the relevant iron- and steel-making technology in use at that time.