Objective: To determine the antioxidant activity of the total flavonoid aglycones (TFA) and its main component pinostrobin chalcone (PSC) separated from the leaves of Caryr cathayensis (LCC). Method: Polyamide column chromatography was used to extract TFA and PSC;the antioxidant activity of TFA and PSC against 2

2-diphenyl-l-picry lhydrazyl(DPPH)

ferric reducing antioxident power(FRAP)

lipid peroxide(LPO) and protein carbonylation(PCO) was assayed. Result: Total phenol content of TFA was equivalent(mg·g-1 extract) to 283.75 mg(gallic acid equivalent)·g-1. The scavenging of DPPH of TFA and PSC are (20.05±1.74)

(11.66±0.61) mg·L-1.The inhibiting of LPO of TFA and PSC are (74.62±5.39)

(24.38±1.24) mg·L-1. The inhibiting of PCO of TFA and PSC are(174.29±11.26)

(86.74±7.89) mg·L-1. The antioxidant assay indicated that both TFA and PSC had a strong antioxidant activity

and except the FRAP activity

all other assay results manifested that the antioxidant activity of PSC was significantly stronger than that of TFA. Conclusion: The leaves of C. cathayensis with high amount of TFA

which with great antioxidant activity

and the compound PSC was the main active component

which was worthy to be further exploited.