Abstract: In order to explore the characterization of the hardness of stainless steel after laser remelting by laser induced breakdown spectroscopy technology, using stainless steel after laser remelting as raw material, the effect of stainless steel with different hardness on the spectral and physical characteristics of laser-induced plasma was studied, the effect of different laser power and scanning speed on the hardness after laser remelting was analyzed, the change rule of different hardness and characteristic spectral lines as well as the change rule of different hardness and plasma electron temperature were analyzed. The experimental results show that the characteristic spectral lines of Fe, Si, Cr and Mn were selected to analyze the relationship between spectral line intensity and hardness as well as the relationship between the ratio of the intensity of spectral lines and hardness, the atomic spectral lines of the elements are negatively correlated with hardness, while the intensity ratio of ionic spectral lines and atomic spectral lines is positively correlated with hardness. Four ionic spectral lines of Fe element were selected to analyze the relationship between plasma electron temperature and hardness. The higher the hardness, the higher the plasma electron temperature, the linear correlation coefficient is 0.919. From this study, it can be shown that LIBS technology has the potential to characterize the hardness of stainless steel after laser remelting, which provides a new method for hardness characterization.