The superplastic deformation and microstructure evolution of solid solution treated 7050 aluminum alloy has been investigated. Tensile were conducted at 420 and 460 °C with the strain rate of 1.0×10-4 ~ 1.0×10-1 s-1, and the deformed samples were characterized using optical microscopy, scanning electron microscopy and electron backscatter diffraction. The results show that the solid solution treated 7050 aluminum alloy gained the maximum elongation of 273% at 460 °C with the strain rate of 1.0×10-2. At the deformation condition, a large part of plastic deformation was completed at an invariable stress. The microstructure transformed from coarse grains to a bimodal microstructure and then to a nearly uniform fine microstructure and the dynamic restoration process is from dynamic recrystallization plus dynamic recovery to dynamic recrystallization with the increasing deform strain during superplastic deformation.