Abstract: 7075 aluminum alloy is widely used in the field of aerospace materials as a structural component due to its excellent properties. There are various radiation particles in the spacecraft space environment, which will cause different degrees of irradiation damage to spacecraft materials, and threaten their reliability, and even lead to failure of space missions. Selecting different doses of 3 MeV Fe¹¹⁺ ions to radiate the 7075 aluminum alloy, using XRD, AFM and nanoindentation to study the microstructure, surface morphology and hardness changes before and after irradiation, the tapered protrusions caused by cascade collision evolution and surface defect diffusion are found on the surface and the surface roughness of the sample increased first and then decreased with the increase of dose. In addition, the nanoindentation test shows that the hardness of the sample increased after irradiation, and with the increase of dose, the hardness gradually became saturated. The analysis shows that the irradiation hardening of the sample is caused by the irradiation defects impeding the slippage of dislocations.