In amine FGD process, great amount of SO42- rapidly cumulate in the amine desulfurization solution. This paper compares the three types of desalination method, respectively Chemical precipitation, ion exchange method and Cooling crystallization, the experiment results show that: Chemical precipitation method can remove 68.51% SO42-, while 97.46% SO32- is separated, Cooling crystallization method, SO42- removal rate can reach 86.45% at 7°C when the molar of Na+ and SO42- ratio is 1.61. Ion exchange method can not effectively remove SO42- from high concentration solution, but considerable Cl- and NO3- is adsorbed by the resin, Cooling crystallization combined with ion exchange resins method can effectively remove SO42-, Cl-, NO3- and other HSS, Obviously better than single ion exchange method.