Due to high protection performance for cut edges, much attention was focused on Zn-Al-Mg coating. Considering hot-dip galvanizing technology was widely applied for the Zn-Al-Mg coating, solidification should strongly influence its microstructure and corrosion properties. In this work, a Zn-Al-Mg alloy was melted in a resistance furnace and then cooled to room temperature with different solidification processes, including water quench, air cooling and furnace cooling. Scanning electron microscopy (SEM) was applied to analyzed the microstructure of the alloys solidified with different processes. Moreover, the effect of solidification on corrosion resistance was studied by electrochemical method. Results show that microstructure of the Zn-Al-Mg alloy consists of Zn-rich primary grains and eutectic of Zn, Al and Mg. It could be found that among others, the furnace cooled Zn-Al-Mg alloy presents the largest size and ratio of the primary grains. With the increasing solidification rate, the primary grains turn to be finer and more eutectic appears, besides, the eutectic transforms from granular-like to lamellar-like. Electrochemical test indicates that the corrosion potentials for all the alloys solidified with different ways are more or less the same level but their corrosion currents and plots of electrochemical impedance spectroscopy (EIS) are remarkable different. The corrosion current of the furnace cooled alloy is the smallest, which means the highest corrosion resistance.