The corrosion inhibition action of imidazole, 1-dodecylimidazole, 1-benzylimidazole, benzimidazole self-assembled films for 316 stainless steel in 0 . 5 mol / L H₂SO₄solution was investigated by electrochemical impedance spectroscopy,polarization curves and quantum chemical calculations. Results showed that four inhibitors were all cathodic inhibitors and performed pretty inhibiting efficiency for 316 stainless steel . As the concentration of inhibitors were 1 X10^-3mol / L,the longer the assembled time,the better the effect of inhibition. The inhibition efficiency of the four inhibitors was up to the value of E_HOMO. The inhibition efficiency of the four inhibitors decreased as follows:benzimidazole>1-dodecylimidazole>1-benzylimidazole> imidazole.