The presence of impurity ions affects the application of magnesium fluoride in subsequent fluoride glass，hot?鄄press?鄄 ed crystals and other aspects，and measures should be taken to reduce the impurity ion content.At the same time，in order to further reduce the cost of raw materials，the industrial grade magnesium sulfate was selected as raw material in the experiment， and high?鄄purity magnesium fluoride which meets the requirements by composite refining，carbonation and fluorination was ob?鄄 tained.The refining process used a combination of redox and chemical precipitation，and the refined solution was carbonated to magnesium carbonate with ammonium hydrogencarbonate，then was mixed with electronic grade hydrofluoric acid to obtain high?鄄purity magnesium fluoride.The results showed that the mass fraction of impurity ions such as Fe and Mn in the magne?鄄 sium fluoride prepared by this process was lower than 5×10-6，which meets the requirement of impurity ion content of magnesium fluoride.It is indicated that it is feasible to prepare high?鄄purity magnesium fluoride according to this method.