Some investigations indicated that triclosan（TCS）has a genetic toxicity and would induce DNA damage.In this paper,a variety of spectroscopic methods，including UV spectrum,fluorescence spectrum and circular dichroism spectrum,were used to study the interaction of triclosan with human tumor related DNA（p53 DNA and C-myc DNA）,aiming at providing the scientific basis for triclosan-s toxicity to human tumor at the molecular level.The UV experiments,KI quenching experiments and CD experiments suggested a weak intercalation between triclosan and DNA;Besides,melting experiments and fluorescence titration experiments also confirmed that triclosan interacts with DNA via partly interaction binding,thus affecting the double helix structure of DNA.