7A85 aluminum alloy，possessing the characteristics of low density，high strength，excellent hot working property，fine weldability，good corrosion resistance and high toughness，has been widely used in aerospace and mechanical structural parts.High temperature rheological behavior and microstructure evolution of as extruded 7A85 aluminum alloy were investigated by optical microscope（OM），transmission electron microscope（TEM）and the unidirectional isothermal compression tests conducted at different temperatures（300，350，400 and 450℃）with different strain rates of 0.01，0.1，1 and 10 s-1.It is concluded that the deformation temperature and strain rate have an important effect on the microstructure of the as extruded 7A85 aluminum alloy after hot compression.With the increase of deformation temperature and the decrease of strain rate（decreasing of lnZ），the subgrains and the recrystallization grains grow，the dislocation density and the quantity of precipitates decrease，and the softening mechanism transforms from dynamic recovery to dynamic recrystallization.Plenty of precipitates of as extruded 7A85 aluminum alloy after hot compression，dispersing in the matrix or along the grain boundaries，inhibit the occurrence of dynamic recrystallization.