The preparation method of fermentation-special peanut cake powder includes: taking peanut cake without mold, crushing and passing through a 40-mesh sieve, taking the undersize to obtain peanut cake powder; mixing peanut cake powder with industrial enzyme preparations, mixing evenly and sending to a twin-screw extruder for extrusion and puffing; drying the extruded and puffed raw material to make the moisture content less than 8-12%; crushing the dried raw material through a micro-pulverizer, with the crushing temperature controlled below 80°C, to obtain fermentation-special peanut cake powder. Peanut cake has high nutritional value, its metabolic energy is the highest among cake feeds, and the crude protein content can reach more than 46%. The vitamin and mineral content is similar to other cake feeds.