Purification method of glycyrrhizic acid

The invention belongs to the technical field of biological medicines, and relates to refining of medical intermediates, in particular to a glycyrrhizic acid purification method, which comprises the following steps: dropwise adding a metal salt solution into an organic solution of a glycyrrhizic acid crude product, crystallizing while dropwise adding the metal salt solution, carrying out primary filtration after crystallizing, adding water into a filter cake obtained by primary filtration for dissolving, and carrying out secondary filtration to obtain purified glycyrrhizic acid; adding a complex reagent to react to generate a precipitate, then filtering for the second time, adding acid into the filtrate filtered for the second time to adjust the pH value to be acidic, separating out a solid, separating the separated solid, and drying to obtain the product, wherein the metal salt is zinc salt, ferric salt and/or ferrous salt, and the complex reagent is pyridine, 2-methylpyridine and/or 4-methylpyridine. The pur