Abstract: In order to explore the mechanism of laser cleaning and removal of rust layer on steel surface. Based on the heat conduction equation, a mathematical model of the surface temperature rise of the steel corrosion layer is established, and the laser power density for removing the corrosion layer is obtained. The error of the laser power density and the known experimental results is about 2%. On this basis, the finite element software is used to analyze the temperature field and thermo-mechanical coupling of the cleaning area, and the temperature distribution characteristics of the rust layer and the substrate are obtained. The analysis shows that when the calculated threshold is used for cleaning, a certain thickness of the rust layer can be removed. At the same time, the substrate temperature is lower than the melting point of the steel, and the surface is not damaged. In addition, the elastic deformation caused by thermal-mechanical coupling facilitates the separation of the rust layer from the steel substrate. The mathematical model of surface temperature rise and the results of thermodynamic analysis presented in this paper can provide theoretical guidance for laser cleaning of the rust layer on the steel surface.