Objective: The determination conditions and antioxidant activity of polyphenol from Diospyros kaki leaf was studied. Method: Color conditions of polyphenol determination by using Folin-Ciocalteu(FC) colorimetric method were obtained

and anti-oxidation activity of polyphenol from D. kaki leaf and a positive control Vitamin C(VC)were determined. Result: The best color reaction conditions of FC colorimetric method were as follows: Folin-Ciocalteu was 1.5 mL

75 g·L-1

Na2CO3 was 6 mL

temperature was 25 ℃

reaction time was 60 min

the standard deviation of its accuracy test was 0.51%

the deviation of reproducibility was 1.02%

and the recovery was 96.7%-100.4%.Free radical scavenging ability in vitro was that: HO·>O2 -·>DPPH·. Half maximal inhibitory concentration(IC50)of polyphenol on HO·

O2 -·

DPPH·were 39.33 mg·L-1

0.53

0.85 g·L-1. And eliminated capacity on HO·and DPPH·went beyond VC

HO·was eliminated by IC50 was only 1/6 of the VC

DPPH·was eliminated by IC50 was 1/3 of the VC. Conclusion: The optimum conditions of determinate polyphenol by using Folin-Ciocalteu method have a well accuracy and repeatability. Polyphenol from D. kaki leaf have strong antioxidation.