A noval β-glucuronidase from Penicillium purpurogenum (PGUS) could catalyze glycosidic bond to release non-reducing terminal β-glucuronic acid residues from glycyrrhizin (GL) into β-mono-glucuronide-glycyrrhizin (GAMG) directly.Previously, we cloned the gene pgus and overexpressed it in Escherichia coli BL21 for high production of β-glucuronidase(PGUS-E).Although a large amount of PGUS-E was produced, the substrate specificity was much lower than that of the corresponding wild strain, the main product was Glycyrrhetinic Acid (GA).