The work aims to investigate the effects of machine hammer peening on improving surface integrity and hardness of aluminum alloy and research on influences of peening parameters on the peening surface quality. The electromagnetic machine hammer peening technology was adopted for 6016 aluminum alloy planarization process. The mechanism of electromagnetic machine hammer peening based on grate path planning was studied and main peening parameters were proposed. Furthermore, the influences of main peening parameters on peening surface quality were analyzed. Taylor Hobson PGI Dimension Profiler, optical microscope and vickers hardness tester were used to obtain surface roughness, topography and hardness of aluminum alloy after machine hammer peening. Results showed that the surface roughness of aluminum alloy could be reduced to 0.05 μm after electromagnetic machine hammer peening and smoothening effect up to mirror-like surface can be attained. Compared to the milled surface, the machine hammer peening could eliminate the milling tracks and there were barely any surface cracks and scratches, showing a good surface smoothing ability. Meanwhile, the hardness could be improved by about 25% to 32%. Small line pitch and feed rate, and high peening frequency were of benefit to decreasing surface roughness and improving hardness. In addition, the line pitch was the most important peening parameter due to its great effect on surface roughness and machine efficiency. Above all, the electromagnetic machine hammer peening is good to 6016 aluminum alloy surface strengthening and planarization that can decrease surface roughness sharply and improve surface hardness. It is a novel, effective and green planarization process technology.