Flavonoids contents and antioxidant activity of extracts from ferns in Tianmu Mountain (China) were investigated in detail. 44 species of ferns were investigated for the first time. DPPH and ABTS free radicals scavenging activities of flavonoid extracts from 44 ferns were investigated for the first time. Total flavonoid contents and radical scavenging potentials of fern allies were lower than those of filicinae. Effects of ecological factors on total flavonoid concentrations and antioxidant activity were significant.