The interaction between salicylic acid(SA)and DNA was investigated by electrochemistry and ultraviolet spectroscopy. The ultraviolet spectroscopy results showed that SA and DNA interacted in an intercalative way. Then SA was further studied by cyclic voltammetry in NaH2PO4–Na2HPO4 buffer solution, pH5.8. SA had a DPV oxidation peak at the potential of 1.070 V(vs. Ag/AgCl)on the glassy carbon electrode. The presence of DNA led to the decrease in the oxidation peak current of SA and the positive shift in the potential. The results indicated that SA was intercalated into the helix structure of DNA and forms an electrochemically inactive supermolecular complex DNA:mSA. Electrochemical method showed a binding ratio of 3∶1 between SA and DNA in the complex, and the binding constant wasβ=2.53×1012.