The wear and corrosion protective films were synthesized on the LC4 Al-Zn-Mg-Cu alloy by microarc oxidation (MAO) technique in an alkali-silicate electrolyte. The microstructure and composition profiles were investigated by scanning electron microscopy and energy dispersive spectroscopy, and the phase structure was performed by X-ray diffraction. The corrosion resistance of coated LC4 alloy was evaluated using potentiodynamic polarization curves. The MAO film consists of γ-Al2O3, α-Al2O3 and amorphous SiO2 phases. The film up to 210 μm contains two layers. The Si element from electrolyte enriched in the outer layer film. After microarc oxidation treatment, the microhardness and corrosion resistance of LC4 alloy were improved significantly.