Amorphous Al2O3 coatings doped with different Si contents on ferritic/martensite steel are successfully prepared by magnetron sputtering technology. The indentation, scratch, tribological tests, and lead-bismuth eutectic corrosion tests with various flow rates, oxygen concentration and temperatures were carried out on the coatings to estimate the application potential for lead-cool fast reactor. The results show that the coatings exhibit poorer toughness than the substrate, the degree of which deteriorates with increasing Si content, and are characterized by brittle fracture in mechanical tests. The Si-doped coatings effectively protect the substrate from LBE corrosion under most conditions and only crack at 650 °C. The causes of cracking are analyzed in detail, providing a case study for the corrosion-resistant coating research.