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Aims: To determine and compare the antioxidant activity of water and ethanol extract of 25 kinds of traditional chinese medicinal plants. Results: The ethanol extract of 4 kinds of medicinal herbs had the strongest scavenging activity. They were Magnolia officinalis, Rheum officinale, Psoralea corylifolia and Radix Bupleuri. In addtion, Rheum laciniatum, Chrysanthemum morifolium, Magnolia officinalis and Salvia miltiorrhiza had the strongest scavenging activity of their water extract. On the basis of the above comparison, we evaluated EC50 and total phenolic content of their ethanol extract. The EC50 of  Magnolia officinalis, Rheum officinale, Psoralea corylifolia and Radix Bupleuri were 2.75mg·mL-1, 11.82mg·mL-1, 25.22mg·mL-1and 42.67mg·mL-1. The total phenlic content of them were 4.80μg·L-1 , 1.19μg·L-1, 1.07μg·L-1 and 0.75μg·L-1, respectively. Conclusion: The results showed the correlation between the antioxidant activity and the total phenol content. Furthermore, the reaction time of the DPPH test affected the free radical scavenging, which reflected the difference of the extract component would impact the test method.