In this study, the GH3039 superalloy sheets were treated by using a Procudo200 laser shock peening (LSP) system to study the effect of LSP on the fatigue life of the GH3039 superalloy. Further, the microstructure and residual stress of the samples before and after LSP were characterized by using an optical microscopy and an X-350A residual stress tester, respectively. The fatigue life tests for the samples before and after LSP were performed by using an MTS Landmark 370.10 electro-hydraulic servo test system, and the fracture morphologies of the samples were characterized by using a ∑IGMA500 scanning electron microscope. The experimental results denote that the grain size of the surface layer of the superalloy is refined by LSP. The average residual stress induced by LSP becomes -255.07 MPa at the sample surface, and the surface roughness increases from 0.0346 μm to 0.048 μm. Furthermore, the fatigue life is observed to be improved by 2.41 times after LSP. Finally, the increase in fatigue life of the LSP-treated GH3039 superalloy can be mainly attributed to the residual compressive stress and grain refinement.