NOVELTY - Preparation of magnesium-containing fertilizer granule includes dissolving brucite in water, adding natural magnesium sulfate and stirring to uniformly mix and obtain magnesium mixed raw material; adding urea, diammonium hydrogen phosphate, potassium and modified starch into spray fluidized bed, blowing hot air in spray fluidized bed, contacting with the material through distribution plate, and obtaining material in fluid state; mixing molasses fermentation liquid, magnesium mixed raw material and citric acid, spray coating with material in fluid state, hot air drying and granulating.    USE - Preparation of magnesium-containing fertilizer granule (claimed).    ADVANTAGE - The method uses brucite, which is a pure natural product having smoothness, uniformity, high hardness and good disintegration property, provides product with high magnesium oxide content, is convenient, reduces dust pollution and waste, uses simple device, and has little increase of cost.    DETAILED DESCRIPTION - Preparation of magnesium-containing fertilizer granule comprises:    (A) taking 55% 80-90-mesh brucite, dissolving in water, adding 45% 60-80-mesh natural magnesium sulfate, adding into a stirrer and stirring for 10 minutes to uniformly mix and obtain magnesium mixed raw material;    (B) adding 40% urea, 20% diammonium hydrogen phosphate, 25% potassium and 15% modified starch into spray fluidized bed, heating direct-fired coal burning hot blast furnace at 1200 degrees C, blowing hot air in spray fluidized bed, contacting with the material through distribution plate, and obtaining material in fluid state;    (C) taking 45% molasses fermentation liquid, 35% magnesium mixed raw material and 20% citric acid, mixing, spray coating with material in fluid state through atomizing nozzle, hot air drying, granulating, and screening by 2 mm and 4 mm double-layer screen, where particles of less than 2 mm are regranulated, and particles of more than 4 mm are pulverized and regranulated;    (D) drying at 200-220 degrees C to water content of 1% by vulcanization bed type dryer and detecting;    (E) preheating fertilizer granule at 80-82 degrees C, heat preserving, preheating 8 g of 5% microcrystalline wax, castor oil and 4 g isocyanate at 100 degrees C, and quickly coating on granule fertilizer surface; and    (F) curing the coated fertilizer granule for 5-6 minutes, cooling and machine sealed packaging.