Abstract: The interrelations among CO,CO₂,O₂ and N₂ in electric arc furnace (EAF) off-gas as well as the effects of oxygen flow and the pool's carbon content on EAF off-gas composition were investigated to perfect studies on the variation laws of EAF off-gas composition. The result shows CO appears under the existence of a lot of CO₂,and its content increases with increasing CO₂ content. The O₂ content is in a linear relationship with the contents of CO₂ and N₂,but in an exponential relationship with the CO content. As the oxygen flow increases,the contents of CO and CO₂ increases,the contents of O₂ and N₂ reduces,and the utilization rate of oxygen improves. The contents of CO and CO₂ achieve the maximum when the mass fraction of carbon in the pool is about 1.3%.