The invention relates to a preparation method of a special carbon-based slow release fertilizer for wheat, and belongs to the technical field of fertilizers. The preparation method comprises the following steps: uniformly mixing polyethylene wax with organic acid, starch, sodium bicarbonate and an alcohols solvent; then placing a mixture into a tube furnace, increasing temperature for carbonization at an inert gas atmosphere, cooling, washing solid residues by using a sodium hydroxide solution, drying, and then grinding to obtain a carbon microsphere; uniformly mixing the carbon microsphere with urea, ammonium phosphate, ammonium sulfate and water, increasing the temperature, cooling, filtering out a solid, and drying to obtain a fertilizer base body; mixing cashew nut oil and hexamethylene tetramine in a reaction kettle, uniformly stirring, then heating, keeping the temperature and cooling, then adding polyhydric alcohol and polyisocyanate, uniformly stirring and mixing, and cooling to room temperature to obtain a coating agent; and placing the fertilizer base body into a fluidized bed coating machine, spraying the coating agent on the rolling fertilizer base body, and drying to obtain a coated fertilizer.