Based on the principles of mass, momentum and heat transfers between the reducing gas and the iron ore solid, a two-dimensional mathematical model for above two phases is established to study the influences of reducing gas composition on thermal and reduction conditions in pre-reduction shaft furnace with the temperature ranging from 1 023 to 1 223K. Due to the strong endothermic effect of iron ore reduction participated by hydrogen (H2), increasing the ratio of carbon monoxide (CO) to H2 enlarges high temperature zone under present calculation conditions, thus improves reduction efficiency inside the furnace. In addition, replacing of the reducing gas with an appropriate proportion of nitrogen (N2) featuring the same temperature has a potential to reduce fuel consumption by as much as 6.5% while the products of similar quality are yielded. © Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg 2011.