Abstract: Glycyrrhizic acid is hydrolyzed to glycyrrhetic acid in vivo. Pharmacological action of glycyrrhetic acid is higher than that of glycyrrhizic acid, so glycyrrhizic acid is a prodrug of glycyrrhetic acid. Chemical structure of glycyrrhetic acid is similar to steroid hormone. Glycyrrhetic acid and glycyrrhizic acid are the inhibitors of enzymes in steroid hormone metabolism, therefore they can enhance effects of endogenic and exogenic glucocorticoids. Glycyrrhetic acid and glycyrrhizic acid, as ligands, can combine with glucocorticoid receptor, but receptor activation is far inferior to glucocorticoid. For this reason, glycyrrhetic acid and glycyrrhizic acid are partial agonists of glucocorticoid receptor. In clinic, glycyrrhizic acid may be used as weak glucocorticoid-like drug, not only enhances glucocorticoid effects but also antagonizes adverse reactions of large dose glucocorticoids.