Abstract: In order to ascertain difference in antioxidant activity of the extracts from the fruiting body of brown Agaricus bisporus at different growth stages， the total polyphenol contents and antioxidant activities of methanolic extracts of the fruiting body at four growth stages including Ayoung mushroom period， Bnormal harvest period， Copen veil period and Dspore matured period were comprehensively compared. The results indicated that there were significant differences in total polyphenol contents and antioxidant activities among the four growth stages. Extracts from growth stage B demonstrated the highest total polyphenol contents and the best antioxidant activities.

Key words: brown Agaricus bisporus, fruiting body, growth stage, total polyphenol, antioxidant activity