By the aid of the surface activities of glycyrrhizic acid, foam separation can be used to extract and concentrate it. The effects of operating parameters such as¯ow rate of air, initial feed concentration, pH and ionic strength on the enrichment ratio and recovery yield of glycyrrhizic acid are investigated in detail. In addition, the in¯uences of other surface-active substances in solution, such as proteins, on the separation of glycyrrhizic acid are also discussed. The experimental results show that foam separation is a simple and effective method to separate and concentrate glycyrrhizic acid.