Tannase was used to extract gallic acid from Coriaria nepalensis bark, and the extraction process was optimized by single factor and response surface experiments. The gallic acid extraction was purified and identified, and the antioxidant activity of the purified gallic acid was investigated and compared with the result of traditional acid extraction method. The experimental results show that when the amount of Coriaria nepalensis bark is used as the benchmark, the extraction yield of gallic acid can reach to10.79%±0.65% under the conditions of 20 u/g tannase addition in extraction pH 5 at 48 ℃ over 4 h. After purification by NKA-9 macroporous resin, the purity of gallic acid prepared by enzymatic method is 96.0%, which is higher than the purity of 81.3% prepared by acid extraction method. Its structure was characterized by 1HNMR, 13CNMR and heteronuclear singular quantum correlation (HSQC). Compared with acid extraction method, gallic acid prepared by enzymatic method has stronger antioxidant activity. When the mass concentration was 256 mg/L, the scavenging rate of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals and hydroxyl radicals were 78.81% and 61.99%, respectively, and the reduction ability value of Fe3+ was 0.685.