In order to continuously improve magnetic property of the recording media, the diffusion control has been strongly suggested as one of the possibilities. However, it lacks quantitative descriptions of the diffusion process to guide the diffusion control design. Therefore, a simplified analytical diffusion model of the Cr diffusion based on general diffusion theory was proposed and discussed in this Z grain boundaries and then diffuses into the article. In this model, the underlayer Cr first fills the adjacent grains, where the initial Cr concentration at the grain boundary was calculated by Fisher's method. A reasonable match between the theoretical and experimental results on saturation magnetization is obtained in both conventional CoCrPt media films and CoCrPt-SiO2 granular media films by analyzing the postannealing experiments. Some possible methods in diffusion control were also discussed.