Abstract: The sticking during reduction of iron ore fines under different atmosphere conditions was studied by using a thermal state visible fluidized bed from 973 to 1173 K.It is found that when defluidization occurs the influences of temperature and reducing atmosphere on the metallization rate of iron ore fines are limited if the superficial gas velocity is constant.At the same time,the surface microstructure of particles when defluidization happens is strongly dependent on reducing gas types and reduction temperature,but it is less dependent on the volume fraction of reducing gas.In addition,with the volume fraction of reducing gas increasing,the fluidization time of iron ore fines gradually decreases,and the mathematical relationship between them was obtained by linear fitting at different temperatures.