In order to investigate the effects of laser shot peening (LSP) on mechanical properties of 6061-T6 aluminum alloy under different strain rates, standard tensile specimens are tested under different conditions like single-side LSP and two-side LSP, followed by the tensile property tests under four different strain rates from 0.0001 to0.1 s-1. The distribution of surface residual stress is measured, and surface roughness before and after LSP is observed. Furthermore, the relation between surface roughness and elongation is also investigated. The grain size and microstructure before and after LSP are analyzed. The results show that the ultimate tensile strength (UTS) and yield strength increases but the elongation decreases with the increment of strain rate. Compared with the untreated sample, the UTS and yield strength after single-side LSP increase slightly, and the elongation decreases by about 1%. After two-side LSP, the UTS increases by 10.8%, and the yield strength increases by 12.5%, the elongation decreases by about 2%. A large amount of grain is refined and the dislocation density also increases in the laser-peened area, which improves the mechanical properties of 6061-T6 aluminum alloy.