Abstract: This paper deals with the mechanism by which berberine decreases the blood glucose level in normal mice. Experiments showed that berberine neither affected insulin secretion or release, nor affected the capacity and affinity of insulin receptor of liver membrane. The hypoglycemic action of berberine might be due to a post-receptor mechanism. Berberine was found to be able to antagonize the hyperglycemic action of glucose injection and inhibit the gluconeogenic action of alanine injection. The hypoglycemic effect of berberine well correlated with the elevation of blood lactic acid level. Therefore, it appears that berberine might produce hypoglycemic effect by inhibition of gluconeognesis and/or stimulation of glycolysis.