Aiming at the cleaning requirements of surface oxide after arc welding of stainless steel car body with excellent performance. The process, mechanism and surface element test after laser cleaning of stainless steel post-weld surface by fiber laser were studied. The effects of laser power, laser frequency and cleaning times on the cleaning process were investigated by comparative experiments with different process parameters, and two possible stripping mechanisms of post-weld oxide on stainless steel surface were proposed. The stainless steel surface after laser cleaning and mechanical grinding was tested. Comparing the results, it was found that the surface cleanliness after laser cleaning was superior than that of the traditional mechanical grinding. This discovery contributes to the widespread promotion of laser cleaning in stainless steel surface dirt cleaning applications.