The FeCl_2·4H_2O crystals were fluidizely calcinated by air in a φ44mm fluidized bed reactor. The process of producing Fe_2O_3 by FeCl_2·4H_2O using fluidzed calcination was studied. The conversion of FeCl_2·4H_2O crystals with reaction time was obtained by measuring the chloride ion concentration in tail gas absorption solutions with chloride ion selective electrode,and process influence factors was investigated,including superficial gas velocity,average grain diameter and bed temperature. The result indic...