Magnesium (Mg) alloys are promising materials for a number of applications in aviation, spaceflight, high- speed rail and automotive industry due to their combination of light weight, excellent shock absorption and recyclability. However, the relatively high corrosion susceptibility of Mg alloys seriously restricts their widespread use. Use of reliable surface protection coatings is an effective method to prolong the service life of Mg alloys and break through the bottleneck of Mg alloy application. Phosphate conversion coatings (PCC) stand out among lots of surface protection technologies for Mg alloys due to its advantages of simplicity, high efficiency and green environmental protection. However, the defects and micro-cracks on the surface of PCC provide a permeable path for water and aggressive ions in a corrosive environment, thus seriously weakening the corrosion protection ability of PCC. Earlier studies have focused on improving the density of PCC by optimizing the process, but in practice the effect on enhancing the durability of PCC is not satisfactory. At present, the construction of high corrosion resistance coatings by integrating PCC with other surface treatment technologies is a research hotspot in the field of Mg alloy corrosion protection.