Rotary drum granulator is mainly used in compound fertilizer production line, with a high fertilizer granules output, suitable for large fertilizer production requirement. Raw materials, such as ammonia, phosphate, nitrogen solution, sulphate phosphate slurry, triple superphosphate(TSP) slurry etc., can be added in the rotary drum to produce chemical reaction. Materials rotate in the drum, cohere with each other, and are turned into compound fertilizer granules at a certain temperature and humidity, accomplishing the whole compound fertilizer production process.