In order to improve the efficiency and reduce the labor intensity, laser polishing technology was used.Laser radiation was used to melt the material layer,the material was evenly distributed on the surface through the surface tension of the material. The 9CrWMn mould steel was used as research object, the optical fiber laser with wavelength of 1 080 nm was used, laser power, scanning speed and defocusing amount were used as variables affecting polishing effect, a set of orthogonal experiments were designed to carry out single-pass polishing experiment on workpiece, and the single-pass polishing marks on workpiece surface after test were analysed. The results show that under the condition of negative defocus, the degree of surface leveling after polishing can be improved by increasing the polishing speed and decreasing the power appropriately.