NOVELTY - Preparing fertilizer comprises adding phosphoric acid and carbamide into a reaction kettle, stirring and reacting the mixture at 96-106 degrees C for 25-35 minutes to obtain an intermediate material, adding potassium hydroxide, potassium phosphate and carbon to the material, reacting the mixture to obtain a slurry, cooling and crystallizing the slurry, adding nitrogen, phosphorus and potassium to the slurry, drying to obtain potassium phosphate mixed product, adding liquid crystal, microelement and sunflower to the product, concentrating and granulating the mixture, drying and stirring.    USE - The method is useful for preparing fertilizer (claimed).    ADVANTAGE - The method prepares the fertilizer with high purity of more than 95% and reduced environmental pollution in an economical manner.    DETAILED DESCRIPTION - Preparing fertilizer comprises adding phosphoric acid and carbamide having a molar ratio of (1.95-2.05) into a reaction kettle, uniformly mixing, stirring the mixture, reacting the stirred mixture having a rotating speed of 50-70 revolutions per minute (rpm) at 96-106 degrees C for 25-35 minutes to obtain an intermediate material, adding 30% of potassium hydroxide, potassium phosphate and carbon to the intermediate material for 2-3 minutes, reacting the mixture at 60-70 degrees C, stirring the reacted mixture having a rotating speed of 35-40 rpm for 45-55 minutes to obtain a potassium phosphate material slurry, cooling the slurry, crystallizing the cooled slurry at less than or equal to 23 degrees C, adding nitrogen, phosphorus and potassium having a ratio of (1.7-1.9):(0.7-0.9):(1.3-1.5) to the crystallized slurry, stirring the mixture, stop crystallizing to obtain a potassium phosphate solution, separating crystal at 90 degrees C, drying the mixture to obtain potassium phosphate mixed product having a purity of 96.3%, adding liquid crystal, microelement and sunflower to the mixed product, uniformly mixing, concentrating the mixture having a moisture content of 16-17% at 98-108 degrees C, stop concentrating to obtain a slurry, placing the slurry into a pelletizer, granulating the mixture, drying the granulated mixture having a moisture content of 4-5% using a machine, and uniformly stirring.