Five psoralen derivatives were synthesized and the structures of them were characterized by 1H NMR and 13C NMR. The antioxidant properties of the compounds were tested by inhibiting the free radical-initiated DNA oxidation and quenching the radical reaction. The results showed that the effective stoichiometric factors (n) of the compounds V and IV could reach 2.00 and 2.11 in the system of inhibiting the DNA oxidation reaction initiated by 2,2’-Azobis(2-methylpropionamidine) dihydrochloride (AAPH). In the inhibition of •OH-oxidation of the DNA system, compounds I ~ V showed antioxidant properties. The thiobarbituric acid absorbance (TBARS) per-centages of compounds IV and V were 76.19% and 78.84%, which were comparable to Trolox (71%). Compounds I ~ V could also in-hibit Cu2+/GSH-oxidation of DNA, and all compounds exhibited good antioxidant properties except compound II (94.00%). All the five compounds were able to trap diammonium 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonate) salt radical (ABTS+•), 2,2-diphenyl-1-picrylhydrazyl radical (DPPH•) and 2,6-di-tert-butyl-alpha-(3,5-di-tert-butyl-4-oxo-2,5-cyclohexadien-p-tolylox radical (galvinoxyl•). The ability of compounds I ~ V to scavenge those free radicals can be measured by the k values. The k values ranged from 0.07 to 0.82 in scavenging ABTS+•, galvinoxyl and DPPH radicals, respectively.