The work aims to study corrosion behavior of high velocity arc sprayed (HVAS) Al coatings. Corrosion behavior of HVAS Al coatings in different experimental conditions was analyzed in rust layer analysis methods including electrochemical impedance spectroscopy (EIS), scanning electron microscope (SEM) microstructure observation, X-ray diffractometer (XRD) and Fourier transform infrared spectroscopy (FTIR). The experimental results were studied comparatively. After 72 h immersion at 3 MPa, corrosion products on the Al coatings became loose powder-like, corrosion pits appeared and the Al coatings failed quickly. After 72 h immersion at atmosphere, the Al coatings were slightly corroded; after 720 h immersion at atmosphere, the Al coatings were completely covered by corrosion products. XRD analysis showed that corrosion products of the Al coatings were similar. FTIR analysis showed that pressure accelerated generation of corrosion products including basic aluminium chloride hydrate Al9Cl6(OH)21?18H2O and Al5Cl3(OH)12?4H2O at 3 MPa. The corrosion products could not adhere to each other and would easily run off at high pressure, hence corrosion resistance of the coatings degraded quickly. Corrosion products of Al coatings at high pressure can not effectively block corrosive medium invading, hence corrosion resistance of Al coatings degraded.