Abstract: Achieving high-quality welding of polycarbonate (PC) materials is an important direction for expanding its engineering applications. The location where the residual stress of the welded parts accumulates is prone to deformation, cracks and other defects. During use, stress corrosion will be formed, which will reduce the strength and shorten the service life of the welded parts. In order to achieve high-quality welding of PC materials, a new method of transmission welding using a copper film coated with carbon black as the laser absorbing material was proposed, and the influence of different laser process parameters (laser power and welding speed) on welding performance, copper film deformation and residual stress was explored. The results show that: with the increase of laser power and welding speed, the shear strength of weld and copper film deformation first increase and then decrease; the width of the weld is proportional to the laser power Proportional and inversely proportional to the welding speed; the residual stress is proportional to the laser power and inversely proportional to the welding speed; and it is found that the deformation of the copper film is beneficial to improve the welding performance and reduce the residual stress to a certain extent.