Abstract: Aiming at the problem that the processing accuracy of the plug-in machine is affected by thermal deformation during the work process, the beam structure of a special-shaped plug-in machine of a company in Shenzhen is taken as the research object, based on the theories of theoretical mechanics, material mechanics, thermodynamics, etc., combined with relevant software, the stiffness characteristics of the beam under the joint action of external forces and temperature are studied. Based on the steady-state thermodynamic analysis, transient analysis is carried out, and the temperature field and shape variables of the beam and the slider change with time are obtained through the transient analysis, and the results show that the time when the beam temperature field reaches the steady state is after 1 875 s, and the temperature of the beam varies greatly from 100 s to 250 s. The maximum total deformation of the beam under the combined action of temperature and external force is 0.354 mm, and the shape variable affected by temperature accounts for about 52.9% of the total deformation; By calculating the position change of the center point of the slider and combining the experimental results, it provides a certain reference for the software compensation error and optimization design in the later stage.