Abstract: This article takes polycarbonate as the research object, aluminum film is used as the intermediate conductive layer, Gaussian surface heat source model is selected, and the metal film thermal stress theoretical model and finite element model are established. The COMSOL software is used to analyze the polycarbonate laser containing the aluminum film intermediate layer. The transmission welding process is numerically simulated. First, the deformation at different positions and the volume strain tensor in different directions are analyzed. Then, according to the simulated equivalent stress cloud diagram and principal stress cloud diagram, the magnitude and distribution of stress in the welding process are analyzed. The results show that the closer to the laser center, the greater the volume strain tensor and the greater the deformation; the equivalent stress at the junction of the aluminum film and the polycarbonate gap is the largest, and the stress at the center point first increases and then decreases with time, and finally tends to stable. The tensile test was carried out with a tensile machine, and the experimental results were compared with the simulation results. It was found that brittle fracture occurred at the junction of the aluminum film and the polycarbonate gap, and the fracture was the same as the stress concentration. The results showed that there is good consistence between them.