Coated compound fertilizer and preparation thereof

The invention discloses an S type coated compound fertilizer and a preparation method thereof. The S type coated compound fertilizer comprises compound fertilizer granules and a coating wrapped on the surface of the granulated fertilizer; wherein, the material for preparing the coating comprises the substances based on the mass portion ratio: 15-27 portions of polystyrene foam, 24-30 portions of recovered Polypropylene polymers, 7-20 portions of low density polyethylene, 10-45 portions of inorganic mineral dust and 2-9 portions of starch or modified starch. The S type coated compound fertilizer has an excellent S type nutrient dissolving mode, can control the release time and amount of nitrogen, phosphorus and potassium nutrient in an intelligentized way, and meets different needs of agricultural production such as culture of seedling, contact fertilizer application and one-off application.