Abstract: The steel industry emits a large amount of CO₂ with dispersed emission sources. The flue gas containing CO₂ has characteristics of temperature fluctuations, low CO₂ volume fraction and complex pollutants, and this increases the difficulty in CO₂ capture. For a total CO₂ volume on the order of one billion tons, not only carbon capture but also the subsequent CO₂ disposal remains a challenging issue that urgently needs to be addressed in steel decarbonization. This paper elaborated on the carbon flow pathways, the functional roles that carbon plays, i.e., fuel, reductant, and raw material, and the conversion reactions within the steel making process. Analysis and review were made on carbon capture,utilization and storage（CCUS） development and application at home and abroad in the steel industry. With overall consideration of the steel capacity projection, process structure trend and H₂ direct reduced iron prospect, this paper proposed an innovative carbon-loop technical route for iron and steel metallurgy. It was given in the premise of reducing primary carbon sources and on the basis of green-power-driven CO₂ conversion, the route works as follows, separating of CO₂ at the terminal end, converting CO₂ into reducing component by green power and recirculating into iron-reducing process. In this manner CO₂-converted component replaced a portion of the primary carbon input, so that to realize the low carbon smelting process. The main point focuses on the building of mass and energy flow model for the blast furnace under extreme coke ratio condition, and we believe it is worthy of attention as carbon neutral pathway for China's steel industry on account of China resource endowment and steel industrial pattern.