Abstract: The reduction behavior of ore powder by co in homemade kg-scale fluidized bed was studied.The reduction degree of the sample increases and the utilization ratio of gas decreases when the reaction lasts longer time, which indicates that the reaction is faster at the beginning of reduction, while it becomes slower in latter process.The higher the reaction temperature, the higher the utilization ratio of gas and the reduction degree are, but the difference of utilization ratio among the different temperatures becomes smaller with time.The utilization ratio of gas can reach about 8% and the reduction degree 80% for 20 min reduction at 850℃, which shows under high temperature the reduction reaction by CO is very fast.The higher the reaction temperature, the higher the apparent reaction rate constant is, but the difference of apparent reaction rate constant among the different temperatures becomes bigger.The increase of reduction degree with gas velocity increase performs quite good linearity, which shows under high temperature even higher velocity of reducing gas can be used to improve the productivity of reactor when CO is used as reducing gas.With the increase of charge height, the metallization ratio and the reduction degree decrease, but the utilization ratio of gas increases.The apparent activation energy of the reduction of 1~3 mm iron ore powder by CO is about 59.11 kJ/mol in the fluidized bed experiment.