Abstract: A CO₂ process emission model was built to calculate the CO₂ emission of iron and steel plants for total and each process. The total emission of a specific plant with the productivity of about 8 million tons per year is 15.61 million tons and the emission intensity is 1.85 t CO₂ for per ton of steel. Calculation results show that the order from the highest emission to the lowest one is BF, coking, sintering, rolling, BOF, flux roasting, and pelletizing process; the BF process and coking process account for 58.83% and 11.25% of the total emission, respectively. The general emission factor (GEF) and carbon saturation index (CSI) were proposed to evaluate the relationship between energy consumption and CO₂ emissions in iron and steel making. It is found that the reduction of CO₂ emissions results from not only energy saving but also the CSI reduction; the CSI has a significant relationship with the energy structure, and the higher percentage of energy with a higher total CO₂ impact coefficient in the energy structure (coke for example) will results in a higher CSI, which has negative effect on the reduction of CO₂ emissions. Developing eco-industrial parks, optimizing the energy structure, and enhancing the energy transform function of iron and steel making all have significant benefit on the reduction of CO₂ emissions.