The interaction between myricetin and calf thymus DNA（ct-DNA） at physiologic pH was investigated by ultraviolet and fluorescence spectroscopy in conjunction with fluorescent probe methylene blue（MB）,circular dichroism（CD） and molecular modeling methods.Thermodynamic parameters（ΔH<0 and ΔS<0） indicated that hydrogen bond and van der Waals play main roles in the binding of myricetin to ct-DNA.The results of spectroscopic experiments suggested that the intrinsic fluorescence of myricetin was quenched in the presence of ct-DNA by static quenching mechanism.The binding constant and the corresponding number of binding sites（n） were calculated to be 1.86×103 mol-1 and 1,respectively.In competition experiments,myricetin was unable to replace MB（an intercalator） from MB-DNA complex,which is indicative of groove binding.Circular dichroism spectra of DNA showed that the attendance of myricetin was not able to change the formation of DNA,which is in agreement with groove binding mode of interaction.Moreover,from molecular modeling methods,a docked structure with minimum energy was obtained,in which myricetin was located in minor grooves preferentially surrounding with A and T rich regions.The results of docking showed that 7-O in A ring and 3’-O in B ring of myricetin were bound with DA18 and DA6 of DNA double helix by hydrogen,respectively.The binding distances were 2.061 ? and 1.918 ?,respectively.