Using ethanol as extraction solvent, tannin was extracted under ultrasonic assistance from persimmon veneer. The optimal ultrasonic-assisted extraction technology was determined by single factor experiment and orthogonal experiment; The antioxidant activity of crude extract and purification were determined by POV measured values and the absorbance values of MDA. The results show that The optimum values of extraction parameters including ethanol ratio, extraction power, extraction temperature and length of extraction were determined by orthogonal array design to be: 50%, 360 W, 70 癈,50 min and the tannin yield was 5.6%. Both the crude extract and purification have antioxidant activity, with an antioxidant sequence of purification > crude extract. Especially, the higher purity had better antioxidant activity . The crude extract exhibits antioxidation for oil when the dosage is 0.08 %, but and it hasn’t synergistic action with VC. 0.04 % purification had good antioxidant effect which is better than VC, but it hasn’t synergistic action with VC.