Corrosion caused by the active chemical properties of magnesium (Mg) alloys seriously restricts their applications in aerospace, transportation, biomedicine, and other fields. Although micro-arc oxidation (MAO) coatings can provide some corrosion protection for Mg alloys, their microporous structure is prone to localized corrosion. Herein, nanoflower-shaped zinc phosphate is prepared and hydrophobically modified. The commercial glue is used to bond the nanoflower-shaped zinc phosphate particle arrays to the MAO-coated AZ31B alloy substrate to produce a two-layer composite coating with superhydrophobic properties. The composite coating exhibits obvious repulsive effects in salt and acidic solutions as indicated by contact angles of 160° and 156°, respectively. The composite coating has improved electrochemical properties and immersion corrosion in both the salt and acidic solutions compared to the substrate and MAO-coated sample. Moreover, the composite coating retains the long-term superhydrophobic effects under different conditions such as immersion in salt and acidic solutions, water scouring, and sunlight exposure, which well indicates commercial applications.