In order to investigate the relaxation rule of residual stress on laser-peening surface of 6061-T6 aluminum alloy during cyclic loading, laser-peening treatment and thermal insulation of 6061-T6 aluminum alloy has been carried out and the surface residual stress under different cyclic stress levels and circle times has been determined. The results show that most of the relaxation of residual stress occurs during the first 10 to 100 cycles, and the stress intends to be steady after 1000 cycles. Larger cyclic loading can cause greater value and rate of residual stress relaxation and even lead to complete release, especially when the peak stress is close to the yield stress. In addition, surface residual stress of the laser-peening specimens treated at 150 ℃ for 10 min is reduced and the magnitude and rate of the stress relaxation are lower. The stability of residual stress during cyclic loading is improved.