Abstract: To study the effect of laser shot peening on the wear resistance of 21-4N valve steel, the valve steel was strengthened by high-power laser shot peening, and then the pin-disc friction tests of the sample treated at 10 J energy were carried out under the load of 20 N and variable load of 20 N to 60 N, respectively. The characteristics such as hardness,roughness, residual compressive stress, microstructure, friction coefficient curve, surface morphology of the friction layer and wear quality of the sample before and after laser shot peening were compared. Finally, the strengthening mechanism of wear resistance of 21-4 N valve steel by laser shot peening was described. The results show that the grains on the surface of the laser shot peening samples are refined, and high residual compressive stress is formed, the surface hardness is increased, and the wear rate of the shot peening samples is obviously lower than that of non-shot peening samples. The surface scratches of the shot peening samples are shallower and the surface wear mass loss is reduced. The analysis shows that the grain refining during laser shot peening increases the surface hardness and strength of the sample, and produces a large residual compressive stress. The serious plastic deformation is produced on the surface of the sample and it further enhances the surface strength of the sample, which slows down the surface oxidation wear rate, thus improving the wear resistance of 21-4N valve steel.