Nanostructured materials have revealed many attractive characteristics, such as high strength and high hardness. However, low ductility is also frequently reported for nanostructured materials. Available experimental and theoretical studies attribute the low ductility of nanostructured materials to a deficit in dislocation activity. Nanostructured Al alloys with a microstructure that contains multiple length scales, from tens of nanometers to hundreds of nanometers, have demonstrated an excellent combination of strength and ductility. The present work involves a theoretical simulation on the tensile deformation behavior and failure process of nanostructured aluminum alloys with a bimodal structure via a unit-cell model. The elastic-plastic behavior and the dynamic fracture process of bimodal materials were simulated by Ramberg-Osgood formula and finite element method, respectively. The numerical results are in good agreement with tensile experimental data.