Abstract: Based on the formation of CIS thin film on a flexible polyimide substrate by Se Ion Beam Assisted Magnetron sputtering technology, a model of the deposit is established. By comparing with the method of conventional gas phase atomic deposition, using ion implantation depth effect as the research object, a calculation method from the perspective of diffusion uniformity is put forward. Through comparison and analysis, when the Se diffusion uniformity is 90%, the substrate temperature needed for ion beam assisted deposition was significantly lower than the substrate temperature needed for gas phase atomic deposition.