The invention discloses a method for preparing organic synthesized bentonite, which comprises: adding sodium carbonate solution or sodium hydroxide solution whose weight percent is 3-8% and mass concentration is 20-30% into natural bentonite to sodium-modify, aging and piling for 12-24 hours after mixing evenly with the temperature of 10-40DEG C, drying until the water content of bentonite is 12-15%, then, adding small organic molecules oxalic acid ammonium powder whose weight percent is 0.5-10% or low molecular weight polyacrylamide powder whose weight percent is 0.1-10%, organic-treating for 8-16 hours, then, rolling until the particle size of the organic synthesized bentonite is negative 200 orders 60-70% through high pressure grinding fibrosis processing, and lastly finely grinding until the negative 200 orders accounts for more than 98%, which is the product. Since the organic synthesized bentonite which is produced by the invention and the granulated iron ore surface produce the chemical force, the hydrophilicity of the granulated iron ore surface is intensified, the green ball strength and the shock temperature are increased, the addition amount of the bentonite is lowered by more than 50%, the green ball falling strength is increased by two times or three times, and the green ball shock temperature is increased by about 60DEG C-200DEG C, which provides high quality furnace burden for intensifying blast furnace ironmaking.