Abstract: The present study aim to illuminate the changes of predominant bioactive components and the antioxidant activity of Pueraria lobata fermented by Eurotium cristatum. The total flavonoid content of solid fermented product and unfermented P. lobata were determined using ultraviolet spectrophotometry. High pressure liquid chromatograph(HPLC)analysis was applied to identify dynamic changes of some specific bioactive components in P. lobata,including puerarin,daidzin and daidzein,and DPPH radical scavenging capacities of fermentation products were also evaluated. The results showed that the content of total flavonoids of P. lobata increased significantly comparied with unfermented P. lobata,and the contents of pueraria and daidzein 1.6,4.9 and 0.5 times higher than those before fermentation but daizin was decreased 1/2,respectively. The IC₅₀of free radical scavenging rate of unfermented product and fermented were(2.2177±0.0484)and(0.8359±0.0047) mg/mL,respectively. There was significant difference between them,which indicating that the antioxidant activity of fermented P. lobata was superior to the unfermented P. lobata. The study could provide evidence for the biotransformation probability of the Chinese herbs and realize the modernization of Chinese traditional medicine.