In order to explore the thermal relaxation behavior of residual stress induced by laser peening on the surface of Nickel- based alloy, a single laser peening treatment is conducted on the surface of IN718 samples, followed by a series of thermal insulation tests conducted on these treated samples. Then the changes of the residual stress, full width at half maximum(FWHM) and grain evolution feature at various test temperatures and exposure time are analyzed. The results show that laser peening can induce compressive residual stress at treated region, enhance the magnitude of FWHM and obviously refine the grains in the near-surface of the material. During the thermal insulation tests, the relaxation magnitude of residual stress is positively correlated with the test temperature and the exposure time. The relaxation speed of residual stress appear to be relatively high during the initial period of exposure, and then slow down with the increases of exposure time. After being exposing by 300 min at 800 ℃, the residual stress relax at a maximum rate of 82.14%. When the test temperature is constant, there is an increase in FWHM value as the exposure time increase. At the test temperature of 600 ℃, the value change of FWHM is found to be slight. After being exposing by 300 min at 600 ℃ , the grain size is still small, which means that the grain refinement effect is still obvious. However, at the test temperature of 800 ℃, the grain grow rapidly so that after being exposing by 300 min, the grain refinement effect almostly disappear.