The work aims to explore the corrosion behavior and mechanism of hot-dip Zn-Al-Mg coatings in a hot and humid marine atmosphere and provide data references for hot-dip Zn-Al-Mg coatings serving in the hot and humid marine atmosphere. The corrosion behavior of the hot-dip Zn-Al-Mg coating in a simulated hot and humid marine atmosphere was analyzed by corrosion weight loss, X-ray diffraction (XRD), scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) and other test methods. The results showed that the corrosion product was mainly composed of Zn5(OH)8Cl2.H2O. After a period of corrosion, a small amount of ZnO and Zn5(OH)6CO3 were found. The corrosion product evolution was related to the participation of Mg in the corrosion process. The corrosion product had a lamellar structure, which was like a "sandwich" at 1 848 h. Compared with the upper and lower layers of dark substances, the bright-colored corrosion product in the middle layer had more Cl elements concentration. The corrosion rate of the hot-dip Zn-Al-Mg coating generally increased with time, and only dropped sharply in the stage of 672-840 h. Comparison of galvanized coatings corrosion in a simulated hot and humid marine environment and zinc corrosion in a hot and humid outdoor marine atmospheric environment showed that the hot-dip Zn-Al-Mg coating had high corrosion resistance in the simulated hot and humid marine atmosphere environment. The evolution of corrosion products of the hot dip Zn-Al-Mg coating in a simulated hot and humid Marine atmosphere is related to Mg in the corrosion process. The reason for the decrease of corrosion rate at 672-840 h is related to the decrease of ZnO and the increase of Zn5(OH)8Cl2.H2O in corrosion products. It is predicted that the hot-dip Zn-Al-Mg coating still has high corrosion resistance in the hot and humid harsh marine atmosphere, and it can be given priority as a construction material for hot and humid marine atmosphere environment.