Abstract: Flavonoids are secondary metabolites of plants. In general,most flavonoids are combined with glucosides and have extremely complex molecular structures. In the nature,these flavonoids have a variety of biological activities,such as anti-oxidation,anti-virus,anti-tumor,scavenging free radicals and so on,however,due to poor solubility and stability of flavonoids,their bioavailability is limited. It has become a hot spot to modify the structure of flavonoids by biocatalytic methods to improve their water solubility or lipid solubility. In this paper,several methods for the modification of the biological structures of flavonoids at home and abroad and the biological activities of modified flavonoids were reviewed in recent years.