Rotary Cooling is used for compound fertilizer production, cooling certain temperature and particle size of fertilizer, matched with drying machines. Can greatly improve the cooling rate, reduce labor intensity and improve production. Further removal of part of the water the reduce fertilizer grain temperature. At the same time it also can be used for other powdery, granular materials cooling, rotary cooler is the main matched machine in rotary kiln production system, its structure is simple, good stable performance, reliable operation. The exhaust gas may be introduced into the rotary kiln after heat exchange, thereby improved the thermal efficiency of the entire system.