Abstract: Denitrification during hot metal pretreatment is studied under laboratory conditions in the range of 1573-1673 K. The results show that the oxygen, sulphur and carbon contents can somewhat reduce the nitrogen solubility in molten iron, and the nitrogen solubility is in linear regression relation with the carbon content. The effects of the initial carbon content on denitrification is obvious. At the same intensity for offering oxygen, the amount of removing nitrogen increases with increasing the carbon content in the hot metal. It is also found that effective denitrification takes place during decarbonizing in the pretreatment. The denitrification ratio is improved with the amount of decarbonization increasing. The lowest nitrogen content at the end point reaches to 13×10^-6, and the denitrification ratio exceeds about 50%, which can meet the demand of ultra-low nitrogen steels for nitrogen content in molten iron.