Abstract: The control release technique can control the release rate of a certain active component in the expect time and enable the active component to maintain a given effective concentration in a certain system.The control release active components will prolong the action time and improve the effects.Many new kinds of chemical fertilizers have been developed with control release technique.Among them the coated fertilizers are most important.In this paper the coated fertilizer has been prepared by coating material,which was prepared by starch,polyvinyl alcohol(PVA)and additives.Effects of additives included with coating materials on the slow release fertilizer were studied in detail.The coated fertilizer has a good slow release character and it can maintain water.The coating material is better than other coating materials that are reported,it is biodegradable and it has no pollution.