The oxidation of calcium sulfite directly affect the final rate of flue gas desulfurization, but the study on the expression of oxidation rate is still in a dispute. Ferrouscatalytic oxidation kinetics of calcium sulfite has been studied with experiments in the oxidation stimulant which is 1.2 m diameter and 1.2 m height. The reaction order of bisulfite ion, ferrous ion and dissolved oxygen were 1, 0.5 and 0 respectively, and the activation energy was 54.52 kJ·mol-1. A kinetic model for the oxidation process of flue gas desulfurization technology has also been set up based on the Fick law and double film theory. Reaction order of bisulfite ion, ferrous ion and dissolved oxygen were 1, 0.5 and 0, and the activation energy was 53.85 kJ·mol-1. With the results of experiment and model, the precision of the model is high with relative error of 1.22%.