The process of smelting solid material to produce composite fertilizer includes the following steps: mixing base material and stuffing crushed to below 2.0 mm, preheating the mixture and adding to molten urea or ammonium nitrate solution through stirring for 3-8 min to produce melt slurry, maintaining the temperature of the slurry at 100-130 deg.c, spraying the slurry with a pump to solid material containing recycled material or partial phosphate or potassium salt to pelletize, sieving to obtain the composite fertilizer product, and returning the fine powder and large grains. The present invention has the features of simple technological process, low cost, environment friendship, etc.