Caffeic acid,chlorogenic acid and forsythiaside are active components of Chinese herbs and have diverse biological activities.As the similar compounds,they all include 3,4-dihydroxy-phenyl in their structures.In this paper,the scavenging effects of the caffeic acid,chlorogenic acid and forsythiaside on H2O2 were studied by means of chemiluminescence.The results show that scavenging effects of caffeic acid and ferulic acid on H2O2 were strong,and,chlorogenic acid,forsythiaside,p-coumaric acid and m-coumaric acid had relative weak scavenging ability,and cinnamic acid had little.The relationships of structure and reactivity indicate that the reactivity of phenolic hydroxyl could be increased if there was a heteroatom with p-tape lone pair of electrons（such as -OH,-OCH3）in the ortho position of it,and phenolic hydroxyl which in the para position of -CHCHCOOH had relative strong reactivity.
