High tower granulation is the process of sending a mixed slurry into a high tower granulator for spray granulation. The granulation material sprayed into the tower by the granulator interacts with the gas resistance rising from the bottom of the tower during the descent process, exchanges heat with it, and falls to the bottom of the tower. The granular material that falls to the bottom of the tower is sieved and surface treated to obtain granular compound fertilizer. No need for drying, no exhaust gas, energy-saving and environmentally friendly.