Abstract: The reduction kinetics tests of Shougang sintering iron ores were performed from 1173 to 1373 K with 100% CO by thermogravimetric analysis, from which the values of reduction reaction apparent activation energy were determined. It could be predicted that the reduction of iron ore sinter is controlled by interracial chemical reaction at the initial stage, and solid-state diffusion at the final stage. According to the unreacted core model and the kinetic model of solid-state diffusion separately, the mutational timing of each rate controlling step was given at various temperatures by using phasewise analysis. The reaction rate constants and solid diffusion coefficients were derived from the kinetic formulas at various temperatures. Changes in morphology were analyzed with an optical microscope, and the mechanism of reduction kinetics was also verified. At the same time, the use of the volume-dwindled unreacted core model in the diffusion stage was proved to be feasible.