Abstract: The iron and steel factory is decomposed into two parts: the material flows process and the energy flows process. The material flow diagram is structured, and the material flow model is constructed accordingly. The energy flow diagram is structured, and the energy flow model is constructed based on the diagram. The calculating model for the CO₂ emissions per ton steel in a factory is constructed, which consists of a variety of factors that have influences on CO₂ emissions. The influences of the materials flows and energy flows on CO₂ emissions in the iron and steel-producing process are analyzed. The models are adopted in a factory to discuss the influences, and the results indicate that some measures should be taken to reduce the CO₂ emissions in China steel industry: ①increasing the material flows from outside of a process and reducing the material flows discharged and recycled; ②reducing the hot iron consumption per ton steel in a converter; ③increasing the output of steel that is produced by electrical furnace; ④improving the electricity generating inside the factory and developing the energy mode of “buying only coal and no electricity"; ⑤enhancing the recovery of residual heat and energy.