Abstract: The process of extracting niobium with solid oxidizer(Fe₃O₄) from hot iron (called SOENb for short) produced in Baotou China was advanced. The optinum process parameters were below:The temperature of hot iron is 1 350℃; W(oxidizer burden weight/hot iron weight) is 5%-10%. The thermodynamical action of Si, Mn, C, P, Nb in hot iron under the actual conditions was discussed and the effect of oxidizer burden on the iron temperature was analysed.