To meet the requirements of low surface residual stresses on the parts made by ultra-precision turning, by finite element analysis and tests, the micron level ultra-precision turning and simulation of aluminum alloy were done. The cutting force and temperature were analyzed, the cause and nature of machined surface residual stresses were studied, and the influence laws of the cutting depth and cutting speed on residual stresses were gotten. Simulation results show that in the cutting process the cutting force was small and the cutting temperature was low, but the unit cutting force was high. The cutting force was the leading factor in forming the compressive stress on the machined surface. The machined surface residual stresses increased with the increase of cutting depth and decreased with the increase of cutting speed. The cutting depth obviously influenced the residual stresses. The experiments of ultra-precision turning in micron level were done and the machined surface residual stresses were measured by XRD. The results of simulation were verified.