The work aims to study effect of laser shock peening on the surface morphology, surface hardness, microstructure and residual stress of slewing bearing steel 42CrMo and further provide guidance for the application of laser shock peening technology in slewing bearing in the future. Laser shock treatment was applied to slewing bearing steel 42CrMo sample with high-power short-pulse intense laser beam. Then, the surface morphology was observed by confocal microscope. The surface hardness of the samples before and after shock was measured by vickers hardness tester. Cross section microstructure was ob-served by scanning electron microscope. Finally, the simulation software ABAQUS was used to simulate the residual stress field after laser shock. In the case of spot diameter of 3 mm, the pulse width of 8 ns, and the laser energy of 2, 3, 4 and 5 J, the maxi-mum depth of micro-pit after laser shock was 2.17, 3.54, 4.67 and 6.07 μm, the maximum hardness of material surface was in-creased by 10.10%, 12.58%, 13.58% and 17.38% respectively and the maximum residual compressive stress of material surface was ?210, ?384, ?495 and ?508 MPa respectively. Microstructure observation results showed that the length and width of lath martensite in plastic deformation layer after laser shock peening were smaller and more uniform than those in base material. After laser shock peening, micro-pit is produced on the surface of slewing bearing steel 42CrMo, and the residual compressive stress is produced on the surface and in a certain depth direction of the material. Within a range of parameters, the maximum depth, surface hardness and maximum residual compressive stress increase as the laser energy increases. The mechanism of laser shock peening to slewing bearing steel 42CrMo is the refinement of lath tempered martensite.