Utilization of biomass in iron ores sintering process as heating agent and reducing agent contributes to energy conservation and emission reduction, and can partially replace for coal and coke. Different biomass powders (pine sawdust, corn straw, and rice shell) were mixed together with goethite ores for roasting process to investigate the mechanism of reduction roasting. The thermal behavior, phase structure and magnetic properties have been thoroughly discussed. The results in this work provide a fundamental understanding for the direct reduction of iron ores separation.