Effects of DNA damage induced by Chinese herbal medicine were studied by differential pulse voltammetric(DPV) method.The voltammeitric behaviour of 8-hydorxy-2-deoxyano-sine(8-OHdG) in the phosphate buffer(pH 5.0) was investigated at a glassy carbon electrode by cyclic voltammetry(CV) and DPV.A well-defined oxidation peak of 8-OHdG at +0.5 V was found，and its current intensity was proportional to concentration of 8.OHdG in the range of 1.0×10-6-7.1×10-4 mol/L.The regression equation was Ip(μA)=0.004 3c(mol/L)+4×10-8(r=0.999 8) and the detection limit(S/N=3) was 3.5×10-7 mol/L.The method was applied in analysis of the levels of 8-OHdG in the calf thymus DNA(ctDNA) exposed to concentration of 40 g/L of glycyrrhiza，cherokee rose，eucommia ulmoides，pinellia，nux vomica extract for 2 h，respectively，and the blood of Kunming mice exposed to low and high concentration of nux vomica extract by mouth injection for 30 consecutive days.The results showed that glycyrrhiza，cherokee rose，eucommia ulmoides，pinellia extract could not cause ctDNA oxidative damage，and nux vomica extract can cause DNA oxidative damage to the formation of 8-OHdG in the average level of (3.2±0.2)μmol/L.The average levels of 8-OHdG were (2.0 ± 0.1) μmol/L and (5.3 ± 0.3) μmol/L in the blood after a long-term administration of low concentration and high concentration of nux vomica extracts of Kunming mice，respectively.The study indicated that nux vomica contained the potential genotoxicity.