This experiment was performed to develop the new desulfurization process which can eliminate the possibility of generation of the secondary pollutants by regenerating the limestone from the sulfite/sulfate slurry generated from the wet lime/limestone flue gas desulfurization process by treating it with the ammonium hydroxide and carbon dioxide and using it again. In the experiments, regent grade calcium carbonate was dissolved to obtain the 200ml of sample slurry of the concentration of 2.0~0.4 weight percent. After three times of regeneration and desulfurization process, the coefficients of regeneration and desulfurization efficiencies are calculated/measured. The obtained results are that the coefficients of generation of the first. second, and third regenerated calcium carbonate were 90.88, 92.13, and 91.50%, respectively; and the desulfurization efficiencies of those are 93.4, 94.2 and 93.0%, respectively.