Polyaniline(PANI) film was electrosynthesized on 304 stainless steel by cyclic voltammetry using aqueous oxalic acid as supporting electrolyte. The potential sweep rates were changed to achieve the PANI film with different thickness and structures. Protective properties of the PANI film for corrosion of stainless steel in 3% NaCl aqueous solution were investigated by monitoring potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS).The results showed that the PANI film which was formed with lower sweep rate led to more positive shift of corrosion potential and greater charge transfer resistance, reflecting higher inhibition for corrosion of the stainless steel.