The improved corrosion resistance contributes to the further application of lightweight magnesium alloys. In thispaper, the microstructure of the AZ41 and AZ91 alloys was analysed using various techniques such as XRD, OM, SEM, and EPMA. The corrosion morphology after immersion was observed. performance of the alloys was assessed in a 0.1 M NaCl solution using EIS measurement, and the corrosion morphology was characterized after immersion. The results show that the oxide film of the AZ91 alloy is relatively intact and more stable than that of AZ41 alloy at the early stages of immersion, resulting in better corrosion performance. However, with increasing immersion time, the connected α-Mg and β-Mg 17 Al 12 eutectic network inhibits corrosion propagation in the AZ41 alloy, while the disconnected eutectic β-Mg 17 Al 12 phase in the AZ91 alloy produces more micro-galvanic couples with the α-Mg matrix, leading to substantial localized corrosion.