Abstract: In view of a practical ironmaking system of a iron and steel enterprise， the carbon flow model of the ironmaking system was established according to carbon balance theory， which can calculate the carbon emission using the practical production data and analyze the influence factors of carbon emission. The relationship between carbon emission and input system energy was analyzed by drawing carbon flow diagram of ironmaking system. The results showed that the model of CO2 emission was coincident with Chinese iron and steel industry and there was a synergy effect between energy consumption and the amount of the carbon emission. The carbon emission caused by energy consumption takes up 95% CO2 emission of the system， and each kind of energy has different carbon emission potential， the emissions potential of coal and coke is larger than that of others. The key points of CO2emissions reducing of ironmaking systems lie in changing energy structure， using clean energy and developing new technology.

Key words: ironmaking systems, carbon balance, carbon flow, energy consumption, CO2 emission reducing