In order to investigate the effect of multi-micro laser shock peening on residual stress of copper materials, surface residual stress is measured, and distribution of residual stress under different overlapping rates and laser energies is explored. Surface mean residual stress is proposed as characteristic means according to the defect of test equipment in existence. Numerical simulation is carried out to display residual stress distribution on top surface and depth in the overlapping process of microscale laser peening. The results show that overlapping rate and laser energy greatly influence the distribution of residual stress, and the surface mean residual stress is an effective characteristic means according to the residual stress distribution along typical paths and mean stress formula.