Objective: To investigate the antioxidant activity of Coreopsis tinctoria extracts in vitro Method: The radical scavenging

hydroxyl radical

superoxide radical and 1

1-diphenyl-2-picrylhydrazyl radical(DPPH) radical by C.tinctoria extracts were detected and analyzed by using spectrophotometry and multiple linear regression analysis.The correlation between contents of C. tinctoria extracts and their antioxidant activity in vitro was surveyed and compared with Vitamin(VC). Result: The radical scavenging capacity of C. tinctoria extracts could be observed in hydroxyl radical

superoxide radical and DPPH radical showed performance. At the selected concentration from 0.2 g ·L-1to 1.0 g ·L-1

the scavenging effects on free radicals had certain dose dependent relationship with C.tinctoria extracts oncentration.When the concentration of 50% Alcoholic eluate from C.tinctoria reached 1.0 g ·L-1

the maximum scavenging rate on hydroxyl radical

superoxide radical and DPPH radical was 86.19%

97.90%

71.85% and its radical scavenging effects could be paralleled to VC. Conclusion: C. tinctoria extracts showed strong antioxidant activities.