Abstract: Based on the constitutive equation of Johnson-Cook model, a meso-scale model of aluminum alloy with void (defects) in ABAQUS finite element platform is established, on the other hand, the crack propagation of Aluminum alloy under complex loading are simulated. The process of crack propagation and crack formation are analyzed. By comparing the model under the single tensile stress crack formation available under complex loading on the structure and material containing defects of harm is very big, and the cracks under complex loading, it is difficult to predicting crack propagation path and the crack extension starting point.