Abstract: The rate of oxidation of ferrous iron in bio-oxidation reactor is the key factor constraining the entire biodesulfurizaion process. Wood chips of two different sizes were used as the immobiliazation carriers of Thiobacillus ferrooxidans，and the kinetics of oxidation of ferrous iron conducted by the biofilm was analyzed. According to the kinetic equation deduced，the data of ferrous iron concentration varying with reaction time was analyzed by the method of non-linear fitting. Thereby the reaction orders were obtained，when two different carriers worked respectively at the optimal aeration rate. And the relationship between the kinetic parameters and the aeration rate were investigated when wood chips (b) was used as the carrier. According to the reaction orders obtained and the data of conversion of ferrous iron varying with the dilution rate under continuous operation，the reaction rate constants in the kinetic equation deducted were obtained by the method of linear fitting as follows，0.9698 h－1·(g·L－1)0.1666、0.9042 h－1·(g·L－1)0.1135. The correlation coefficients between prediction model and experimental data were all higher than 0.99，indicating that the kinetic model was suitable for prediction.