Deoxyribonucleic acid (DNA) was investigated for suppressing copper corrosion in 0.5 M H2SO4 through electrochemical measurement, microscopic surface observation, X-ray photoelectron spectroscopy (XPS) analysis and molecular dynamics (MD) simulation. Results indicate that DNA acts as an effective cathodic-type inhibitor that mainly suppresses cathodic reaction by forming anchored DNA-adsorption film. The film shows active blocking effect, obeys the Langmuir adsorption model and involves physisorption and chemisorption. The MD simulation gives the new insights at molecular level and indicates the formation of an interesting double barrier of DNA molecule on the Cu (111) surface due to its unique twist structure.