Based on the “fatigue strength test study on rated details of aluminum alloy double shafts”, a sub-project of the national major engineering project, taking the cross-shaped aluminum alloy sheet as the research object, the finite element software ANSYS Workbench was used to model and simulate. The stress distribution, deformation and fatigue life of cruciform aluminum alloys under cyclic loads with phase difference of 0, 90°and 180°were studied. The difference of biaxial force of aluminum alloy under different phase difference was compared and analyzed and the visualized graphics, images and calculation results were analyzed. Finally, the actual deformation and theoretical analysis were basically identical by comparison with the experimental results. It shows that the model of cross-shaped aluminum alloy specimens established in ANSYS Workbench is accurate and reliable. The central circular hole area should be monitored in the biaxial fatigue test of the cruciform aluminum alloy.It provides basic technical support for structural design and strength evaluation of aluminum alloy for large aircraft.