After metallizing aluminum on the magnesium alloy surface, it was held at the temperature 430℃~450℃ for one hour in order that the combined surface of magnesium and aluminum produces the molten diffusion and forms a metallurgic anticorrosion coating. It was revealed by the experiments and analyses that the metallizing aluminum coating was firmly combined with the magnesium alloy being as the base material and the excellent anticorrosion property could be obtained.