Abstract：8-(dimethylamino) Methyl Myricetin (8-MYR) was totally synthesized starting from paraformaldehyde, dimethylamine and myricetin(MYR) and all compounds were characterized by IR, 1HNMR,13C-NMR, EI-MS,and elemental analysis. This article focused on the theoretical and experimental research on the antioxidative activity, DNA interactions and antitumor activities of 8-MYR and MYR in vitro,which was evaluated by Fenton-like reaction experiment, UV-Vis absorption and MTT method ,respectively.The results showed that 8-MYR and MYR had a certain ability to scavenge hydroxyl free radical and the scavenging ratio of them treated with10 μmo/L were 63.6% and 61.3%,respectively. In the electronic spectr , appreciable hypochromism can be observed for the two complexes with increasing amounts of DNA.and the Kb values of 8-MYR and MYR were 4.15×105(mol/L)-1and 3.38×105(mol/L)-1,respectively.The results of MTT assay showed that 8-MYR had significantly cytotoxic effects on HepG2 and LO2 and the IC50 value of 48 h were (183.40±11.96)μmol/L and (304.45±4.60)μmol/L,respectively.In a word，compared with MYR,8-MYR had the stronger antitumor activity,scavenging effects on hydroxyl radicals and interaction with CT-DNA.