Abstract: In the process of promoting the construction of the company's physical inspection intelligent sample preparation project, through a large number of physical tests, a comparative analysis of metallographic examination and microhardness was carried out for different steel grades, and the precise quantitative width of the laser cutting heat-affected zone was clarified. The results show that the width of the heat-affected zone after laser cutting was not necessarily related to the thickness of the plate. Different steel grades showed different microstructure and hardness changes in the heat-affected zone after laser cutting. The heat-affected zone of carbon steel was obvious, which may affect its mechanical properties. The width of heat-affected zone and the change of microstructure of stainless steel with different microstructure after laser cutting were different. The results provided a practical basis for the subsequent process to reasonably reserve the finishing allowance and improve the processing efficiency. It was also a refinement and supplement for the selection of laser cutting allowance in the GB/T 2975—2018 standard.