Fe - 10Cr nanocrystalline （ nc ） coating with the grain size about 20 nm to 30 nm was fabricated on a glass substrate by magnetron sputtering technique. The corrosion behavior of the Fe - 10Cr nc coating and its counterpart alloys were investigated in 0.05 mol/L H2SO4 ＋0.25 mol/L Na2SO4 solution by polarization curves. The resuits showed that the active dissolution of Fe - 10Cr nc coating was accelerated as comparing with its counterpart Fe - 10Cr cast alloy. For Fe - 10Cr nc coating,it had a higher tendency to passive in acid solution and the passive current density was lower as compaed with its counterpart ahoy. The further average active energy measurement, EIS measurement and Mott -Schottky analysis revealed that the average active energy for the dissolving reaction of the Fe- 10Cr nc coating was higher. This is attributed to the higher defect density on the nc coating. On the other hand,even though the same n type semiconductor passive film was formed on both nc sputtering coating and its counterpart alloy,but Cr was easier to accumulate in the passive film of Fe - 10Cr nc coating and the donor density in its passive film was lower. The higher passive ability of the nc sputtering coating was attributed to the more Cr accumulated in the passive film and the higher chemical stability of the passivity film.