In order to determine the optimum joint conditions, four key process parameters affecting the joint quality of laser transmission joint of 1mm thick PET film and PC film，namely，laser power, scanning speed, clamping pressure and scanning number are optimized by response surface methodology in this paper. The interaction effect of main process parameters on joint quality is researched. The samples are tested using a multi-axis microtester in order to determine joint strength. The morphology of the joining area is observed with an optical microscope. Design Expert analysis indicates that the best laser power, scanning speed, clamping pressure and scanning number on joint quality were 35.7W, 5.0mm/s, 0.75MPa, 3, respectively. Finally, the experimental results are consistent with the predicted, which illustrates that the developed mathematical models can predict the responses adequately.