Nanoindentation method is suitable for testing the mechanical properties of micron scale grains to ensure the effect of the second phase. In this experiment, the relationships between hardness, elastic modulus and the work of 7075 aluminum alloy grains with different single wall carbon nanotubes content were investigated. The results show that grain size decreases with the increase of single wall carbon nanotubes(SWCNTs) content, and MgZn2 and Al2Cu can be found. Hardness, young's modulus and the elastic reverse deformation of 7075 aluminum alloy increase firstly with increasing single wall carbon nanotubes, and then decrease obviously with the further increase of single wall carbon nanotubes, while the mechanical work and the plastic deformation work of the alloy have an opposite trend. It can be conclude that the single-walled carbon nanotubes at the grain boundary obviously changed the strain.