The influence of potential on contact angle and the effect of TPB width on the cathodic corrosion processes of metals were studied by steady polarization and EIS technique combined with contact angle measurement. It is found that both cathodic limiting current density and corrosion current density linearly increases with increasing the TPB width, confirming the important role of TPB width in gas/liquid/solid multiphase corrosion systems. Based on above results, the effect of water film thickness on atmospheric corrosion rate was quantitatively evaluated by the TPB width.