In view of the low calculation accuracy for laser cutting speed when cutting stainless steel plates, the stainless steel material characteristics were analyzed, MATLAB software was used to fit the data of specific heat capacity and thermal conductivity at different temperatures, and the functional relationships between specific heat capacity and temperature, thermal conductivity and temperature were obtained respectively. Then, the energy transfer law in the process of cutting stainless steel plate by laser was analyzed, and the heat balance equation was established in combination with the law of conservation of energy, i.e. the total energy absorbed by the material was equal to the sum of the energy absorbed by heating the slit material to the melting point, the energy lost in heat conduction and the latent heat of melting of the material, and the functional relationship between cutting speed and other process parameters was deduced.Finally, an experiment was carried out on a laser cutting machine. The cutting experiment results show that the calculated cutting speed is in good agreement with the optimal cutting speed obtained by the experiment, and the method can be used to guide the actual processing.