Self-assembledmonolayers (SAMs) of 2,5-Diphenyl-1,3,4-oxadiazole (PPD) synthesized by 2-ary1 hydrazine were fabricated on carbon-steel surface.The preparation conditions and corrosion inhibition of PPD SAMs were investigated by electrochemical measurement and surface analysis techniques. The inhibition mechanism of oxadiazole was further discussed by quantitative calculation. The results showed that the film assembled at4 mmol•L-1 concentration for 12 h possessed the best inhibition efficiency,which was up to 91.95%.The monolayers on the steel surface were detected through the X-ray photoelectron spectroscopy (XPS). The active region was verified by quantum chemistry calculation.