<p>The applications of Al alloy foam require consideration of potential damage risks, which are closely related to the evolution of its internal pore structures. However, conventional ex situ experimental observation cannot provide information on the structure evolution during deformation. In order to investigate the failure mechanism of Al alloy foam under quasi-static compression, by utilizing X-ray imaging technology, in situ CT image data were obtained during the loading process. A geometric model characterizing the real structure of Al alloy foam was reconstructed from the initial CT images and used for finite element simulation. Besides, based on the digital volume correlation (DVC) method, the displacement and strain fields of Al alloy foam were calculated. The results show that the in situ experimental observation based on X-ray imaging can effectively obtain the failure information of Al alloy foam. The simulation results for deformation and failure behavior of Al alloy foam are consistent with experimental results. During the quasi-static compression, a shear band can be observed diagonally across the profile of Al alloy foam, with weak regions occurring in the cells with larger volume and higher aspect ratios. Using these weak regions as boundaries, the relative displacement of cell structures on one side compared to another side was identified as the intrinsic cause of shear band formation. The high-strain regions identified by DVC closely match the crack locations on the cell walls, validating the accuracy of DVC on localizing cracks on cell walls and predicting their propagation trends.</p>