Abstract: To investigate the antioxidant activity of isochlorogenic acid A in vitro and in vivo. Isochlorogenic acid A from honeysuckle herbs was extracted.The antioxidant activities of isochlorogenic acid A was evaluated by spectrophotometry on its ability of scavenging ·OH, O^-2·, DPPH· and the reduction force.The zebrafish was used to test the antioxidant activities of isochlorogenic acid A in vivo.The result showed that the isochlorogenic acid A had well scavenging activity to DPPH, ·OH and O^-2·in the range of experimental concentration, the highest scavenging of DPPH and OH were reached 97.04%, 60.01%respectively.However, the highest scavenging of O^-2· reached just 28.04%. Determination of OD in reduction ability of isochlorogenic acid A up to 0.98, illustrating that isochlorogenic acid A had a highly reduction ability. In vivo experiments in zebrafish showed that the antioxidant capacities were reached to 60.4%, when the concentration of sample were 25 μg/m L. So the isochlorogenic acid A showed effective antioxidative action both in vitro and in vivo.