<p>The solidified microstructure and the corresponding surface corrosion resistance of the Zn-Al-Mg coated product were experimentally investigated, and the effects of cooling rate and alloy composition on the coated products were fully analyzed by means of CALPHAD (CALculation of PHAse Diagrams) calculations. Scanning electron microscopy, electron probe micro-analyzer, X-ray diffraction and glow discharge spectrometer methods were applied to study the micro-morphologies, phase compositions, phase structures and elemental distribution of Zn-Al-Mg alloy coatings resulting from different cooling rates, respectively. The Tafel polarization test and electrochemical impedance spectroscopy test were carried out to investigate the electrochemical feature of Zn-Al-Mg alloy coatings. It was found that the enrichment of Mg on the surface of the Zn-Al-Mg coating impairs its surface qualities. With the assistance of thermodynamic and kinetic simulations, it is suggested that both the cooling rate and the solidification sequence led to the enrichment of Mg on the coating surface. Alloy coatings including MgZn₂ phase at faster cooling rates have higher Mg enrichment on the coating surface. Therefore, it is necessary to have the phase transition MgZn₂↔Mg₂Zn₁₁ occur in the final solidification stage, reducing the Mg enrichment on the coating surface. The redesign of the alloy composition is aimed at changing the solidification sequence of the Al-rich Fcc_A1 phase and Mg-rich Mg-Zn compound and adjusting the ratio of the eutectic and primary phases, which can further improve the coating qualities of the industrial Zn-Al-Mg coated products.</p>