The invention relates to a preparation method of a fermented forage mulberry feed. The preparation method includes steps of: 1) preparation of a compound microbial culture liquid: placing taro, Chinese yam, forage mulberry, glucose and agar into a conical flask with addition of water to perform high-pressure sterilization; 2) resuscitation and enlarging cultivation of the compound microorganisms,production of medium Qu, and fermentation of the forage mulberry powder: uniformly blending the forage mulberry powder, meat bone powder, wheat bran and sweet corn flour, adding water and kneading themixture with hands into dough without water dropping from finger seams, adding the air-dried medium Qu, uniformly blending the materials, placing the materials in a fermentation tank at 25-36 DEG C,after 36-72 h, removing a plastic thin film and turning the materials, cooling the materials to normal temperature, and waiting for 24 h to prepare the fermented forage mulberry feed. The method is simple in operations, wherein the forage mulberry powder is subjected to artificial fermentation with screened yeast, lactic acid bacillus, aspergillus oryzae, cellulase and xylanase, so that mouth feelof the forage mulberry powder is improved well and feed intake of animals is improved. The product is rich in probiotics flora, so that digestion and absorption of the forage mulberry component are improved.