Abstract: The Nb extraction process in Baotou Steel Company is a process accompanied with the iron and steel-making process, in which the blast furnace smelting is one of the main step of extracting Nb. It was discovered by experiment that niobium oxide could be turned into niobium carbide(NbC) during carbonthermal reduction and the detained NbC layer exised at the metal-slag interface. The existence of tne detained NbC layer obstructs the entering of Nb into iron and has bad effects on the Nb recovery ratio. NbC can dissolve into liquid iron. Raising temperature is favourable for the increasing of the solubility of NbC in iron and the raising of Nb recovery ratio.