Abstract: The effect of hot extrusion at 340-460 ℃ on the microstructure and hardness of 7075 ultra-high strength aluminum alloy was studied by SEM, EBSD and Vickers hardness tester. The results show that with the increases of extrusion temperature, the deformation structure decreases gradually, the recrystallization structure increases gradually, and the average grain size increases gradually. The grain size of extruded alloy at 340℃ is the smallest, which is 3.43μm. With the increase of extrusion temperature, the hardness of 7075 aluminum alloy decreases gradually. The hardness of 340 ℃ extrusion alloy is the highest, which reaches 96.9 HV, and the hardness of 460 ℃ extrusion alloy is the lowest, which is 87.6 HV.