Abstract: The process of sticking of Fe₂O₃ and iron particles during fluidization was investigated with a visual fluidized bed reactor.The results showed that Fe₂O₃ would defluidize in reduction gases but not in inert gases,and the sticking point happened around the initial stage of iron nucleation.The sticking of iron particles was observed in both reduction and inert gases.It is indicated that the premise of sticking was the formation of iron.When the fluidization temperature increased from 700℃ to 750℃,the critical point of sticking occurred 11 min in advance.It is the temperature-determined surface property of metallic iron that leads to the sticking.Scanning electron microscope(SEM) analysis proved that the sticking of Fe₂O₃ in fluidized bed reduction resulted mainly from iron surfaces with nano/micro structures.