Abstract: Understanding the influence of purities on the electrochemical performance of pure aluminum (Al) in alkaline media for Al–air batteries is significant. Herein, we comprehensively investigate secondary phase precipitate (SPP)-induced localized corrosion of pure Al inNaOH solution mainly based on quasi-in-situ and cross-section observations under scanning electron microscopy coupled with finite element simulation. The experimental results indicate that Al–Fe SPPs appear as clusters and are coherent with the Al substrate. In alkaline media, Al–Fe SPPs exhibit more positive potentials than the substrate, thus aggravating localized galvanic corrosion as cathodic phases. Moreover, finite element simulation indicates that the irregular geometry coupled with potential difference produces the non-uniform current density distribution inside the SPP cluster, and the current density on the Al substrate gradually decreases with distance.