Abstract: According to the reduction kinetics characteristics of industrial production of sinter， a new model concerned chemical reduction kinetics and molecular diffusion of the cubic particles in different states of reduction process was established on the basis of mass transfer of metallurgy transport principle and the basic principle of the chemical reduction. The sectional stepwise method was adopted to study the reaction kinetics of the sinter particles reduced by CO. Then the switch point of the different ratelimiting steps and the relevant kinetic parameters were obtained. Finally， the relationship between the kinetic parameters and temperature was determined. Moreover， the accuracy of distinguishing different ratelimiting steps of this model and its rationality was verified through the observation of the microstructure evolution during the reduction process of sinter ores. Therefore， the sectional stepwise method determined the switch point of different ratelimiting steps and the relevant kinetic parameters， which can be universally used in the investigations of dynamics of other reaction process.

Key words: reaction kinetics, sectional stepwise method, sinter ore, kinetic parameters, cube