A multi-scale model is developed to link the continuum damage variable in macroscale to the number density of multiple pits and cracks in microscale for studying the corrosion fatigue of aluminum alloy from multi-scale viewpoint. The developed model is used to predict the coherent multi-scale corrosion fatigue process of aluminum alloy component in the 3.5 wt% NaCl water solution under constant stress amplitude at a nominal frequency of 5 Hz, and the numerical prediction results are compared with the experimental results. It shows that the model is effective and can be used to study the corrosion fatigue mechanisms of aluminum alloy from both macro- and microscale viewpoints.