Abstract: Electrodialysis recycling principle of sodium alkali flue gas desulfurization(FGD)was studied with anion-exchange membrane and model deduction.Results show that in the process of sodium alkali FGD with anion-exchange membrane electrodialysis recycling，theoretical and practical sulfur electrodialysis ratio were almost the same and increased with the level of current density.Sulfur electrodialysis ratio could be calculated according to the pH of cathode influent and effluent solution.The model was in good agreement with the experiment results and reflected the electrodialysis effect well.Sulfur electrodialysis ratio should be less than 50% and it would increase quickly at pH=6.0—7.5 and increase slowly at pH＜6.0 or pH＞7.5.The model had good stability in the stated range of influent solution pH.