2196-T8511 Al-Li alloy extrusions. Each material involved four kinds of cross-section extrusions. The true stress-strain curves and mechanical properties of different cross-sections, the different sidewall and different thickness were determined. Irregular tear zone and dimples are distributed everywhere by observing the fracture surface of Al-Li alloy. Dimples in 2196-T8511 are smaller and shallower than the 2099-T83 Al-Li alloy, indicating that the plasticity of 2099-T83 Al-Li alloy is better, which is consistent with the mechanical properties.