Abstract: As a typical resource and energy intensive industry, energy saving and emission reduction is the effective green and low-carbon transformation and development path of the iron and steel industry. Energy-conservation technologies are vital to improve energy efficiency, reduce carbon emissions and decrease air pollution in the iron and steel industry. The Conservation Supply Curve method was used to evaluate the techonolies’ energy-conservation cost of the iron and steel industry in the Yangtze River Delta region. And the energy conservation potential realized by the technologies in the region in 2030 was evaluated. The results showed that 28 energy-conservation technologies in the iron and steel industry were expected to save 875.74 PJ of energy in 2030, which was about 34% of the total energy consumption of the iron and steel industry in the Yangtze River Delta in 2020. When different income items were considered, the energy-conservation cost of technologies was different; when no income was considered, the energy-conservation cost of technologies was the highest; when the co-benefit was taken into account, the energy-conservation cost was reduced to a lower level. The discount rate, the trading price of greenhouse gases or pollutants and other factors would have an impact on the energy-conservation cost of the technologies. The higher the discount rate, the higher the capital cost, and the higher the energy-conservation cost of the technologies. A rise in the price of greenhouse gases or pollutants would increase the benefit of energy conservation and thus reduce the cost of energy conservation of the technologies.