Abstract: An aluminous honeycomb sandwich panel with some structural damages was selected as the objective in this study. The panel was simply supported along four edges and its vibration shape data was collected through modal experiment with a hammering method. The damages with different degrees at different positions of the honeycomb sandwich panel were identified by three identification methods, i.e., the modal difference of vibration shape, the curvature mode and the Gaussian curvature mode, respectively. It is found that the modal difference of vibration shape at the damage location is obvious when the honeycomb sandwich panel has some structural damages. This indicates that the damage location can be accurately identified by using the difference of vibration shape. Furthermore, the damage degree can be identified according to the difference at the damage location after the damage location is defined.