Abstract: The corrosion morphology of aluminum alloy was obtained by SEM. With the aid of digital image technique, original SEM images were transferred to binary image, which was prepared to be executed with fractal analysis. Relationship between fractal dimensions of binary images versus corresponding corrosion damage was identified. Results indicated a complicated relationship of grey threshold value and corresponding calculated fractal dimension, which was similar to the elastoplastic tensile curve. Corrosion damage could be characterized from viewpoint of fractal geometry, which would be promising for engineering application.