NOVELTY - Fertilizer is produced by heating urea melt high tower via heat transfer oil recirculation to obtain urea melt liquor. The urea melt liquor is used as fluid carrier to mix fully with powdery monoammonium phosphate, potassium chloride or potassium sulfate and auxiliary material to form slurry. The slurry is dispersed as droplets via a pelletizing device on pelletizing tower top. The droplets fall off under action of gravity, and contact widdershins with cold air entering from bottom of pelletizing tower. The droplets are then, cooled and solidified to fall freely as fertilizer particles.    USE - Method of producing fertilizer (claimed).    ADVANTAGE - The method has high use ratio of energy, and reduces wastewater and environment pollution.    DETAILED DESCRIPTION - Production of fertilizer comprises heating urea melt high tower via heat transfer oil recirculation, and pelletizing via high tower. The urea melt liquor is used as fluid carrier to mix fully with powdery monoammonium phosphate, potassium chloride or potassium sulfate and auxiliary material in a mixing tank to form slurry and dispersed as droplets via a pelletizing device on pelletizing tower top. The droplets fall off under action of gravity and buoyancy force and contact widdershins with cold air entering from bottom of the pelletizing tower. Then, the droplets are cooled and solidified to fall freely as fertilizer particles. The melt urea liquor is prepared by adding urea into a urea melting tank and feeding heat transfer oil at 150-160 degrees C from a coiler of the urea melting tank to heat and melt the urea. The heat transfer oil coming out from the coiler of the urea melting tank returns back to a heat transfer oil furnace to be heated, recycled and used. The melting of urea involves injecting oil to a high-position oil tank via a low-position oil tank, observing liquid level of the high-position oil tank, determining the oil injection in place, and then igniting to heat a heat transfer oil furnace; starting a circulating pump to fully circulate; and heating slowly to warm the oil in the furnace to 60-80 degrees C and make the moisture in the oil evaporate for 20-30 minutes, then warming to 150-160 degrees C gradually, and allowing the oil to enter into the coiler of the urea melting tank to melt the urea. In the heating process, the liquid level of the high-position oil tank is maintained and oil is supplemented when it is below the liquid level, while half of oil level of the low-position oil tank is maintained.