Abstract: In order to explore the influence of picosecond laser processing on the surface properties of stainless steel and verify whether the laser processing can damage the substrate, the surface of oxidized stainless steel was cleaned by picosecond laser with the cleaning times of 1, 400 and 800, respectively. The oxide layer was removed and the stainless steel substrate was processed at the same time. The surface roughness and cleaning thickness were detected by White Light Interferometer. The surface morphology and composition distribution of stainless steel were analyzed by SEM and EDS.The microstructure was observed by metallographic microscope. The surface and section hardness of the samples were measured by micro Vickers hardness tester. The results show that, once picosecond laser cleaning can remove the part of the oxide layer on the surface of stainless steel, the oxide layer is completely removed and the substrate is partially removed at 400 and 800 times, and the removal depth increases with the number of times. The surface roughness decreases gradually. The increase of laser processing times results in slight oxidation on the surface of substrate. The microstructure of the matrix does not change with the increase of times, which is still dominated by austenite. The hardness of stainless steel section is similar to that of 316L after different times of laser processing. The picosecond laser cleaning can remove the oxide layer and matrix, and it has no damage effect on the matrix material and no change in the mechanical properties.