The surface of the K403′s thin slice specimen uses laser shock processing technology in order to strengthen the surface on the nanocrystallization, located on the surface of the specimen, for the cast parts of the nickel-based superalloy K403, which produced cracks, corrosion, and wear. The formation mechanism of the nano-crystal layer on the surface was analyzed by these technologies using X-ray diffraction(XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The results showed that a nanocrystalline layer of 226 nanometers thick could be prepared by laser-induced high-pressure plasma shock wave on the specimen′s surface. The results of XRD and SEM showed that it will not change the phase structure by that laser shock processing the refined surface grain structure. Under the high pressure, the surface microstructure of K403 specimen generated a great number of dislocations and refinement grains into nanoscale.