A release system for controlled release fertilizer was developed for practical use, which was composed of main tube for holding fertilizers and branch tube for releasing nutrients. Natural and semi-natural materials such as chitosan and pectin were used as gel materials in branch tube, and the controlled release effect was checked in laboratory. The results showed that the nutrients in release system were released linearly, and a good controlled effect was observed. The nutrients release was modeled respectively according to the Second Fick Diffusion Law and Ohm law, and the results were almost the same. The nutrients release was mainly controlled by diffusion coefficient, resistance, diffusion area and thickness of gel materials. From this model nutrients were released linearly, which agreed with experimental result, and then the diffusion coefficient and resistance were evaluated, which gave a theory basis for further application.