Abstract: The tuyere annulus of hot metal pretreatment process was often blocked up by deposit carbon when light oil was used as coolant and the operation of tuyere cooling was very unstable. A new method was studied in which N₂ and CO₂ was blown with oil simultaneously, in order to prevent the carbon deposition from annulus and improve the stability of the tuyere cooling. This method is very effective for stable tuyere cooling.