The drum granulation method is a method of mixing and granulating powdery basic fertilizers using a rotary drum granulator, and is especially suitable for large-scale production of cold and hot compound fertilizer granulation lines and high-low concentration npk production line. The main working method is wet granulation. Principle: each basic fertilizer is first screened separately, and the screened material is crushed by a crusher and then screened. The undersieves are sent to their respective warehouses. When the granulation system is running, all basic fertilizers are sent into the hopper from their respective warehouses in proportion to requirements through metering equipment, conveying equipment and lifting equipment at the same time. At the same time, the return material also enters the warehouse through the lifting equipment and basic fertilizer.