Zn-Al diffution couples were formed by ion implantation. The diffusion model of impurity atoms in single-phase region was suggested for the case that the implanted concentration was less than its solid solubility in host. Zn diffusion profiles calculated from this model with numerical method were in good agreement with the results of experiment. By the enhanced diffusion effect accompanied with ion implantation, the diffusion coefficients of Zn in polycrystalline Al between 260-380℃ were obtained, which were difficult to determine using conventional deposition method.