The invention provides a method for preparing a biological feed by taking manioc residues as raw materials. The method comprises the following steps of: preparing fermentation strains and fermentation mother cultures from aspergillus, bacillaceae, lievito and lactobacillus, and performing mixed fermentation by taking the manioc residues as the raw materials to obtain a biological feed crude product; and mixing uniformly, crushing, sieving, drying and packaging to obtain a biological feed finished product. According to the method, the manioc residues are used as the raw materials, so the biological feed is low in cost and wide in source, industrial waste residues are recycled, and the problem of the pollution of the manioc residues is solved. Simultaneously, the strains which are high in cellulose degradation effect and high in yield of mycoprotein are selected, so that cellulose in the manioc residues is degraded fully, the protein content of the feed is improved, a large number of enzymes, beneficial viable bacteria and organic acids are added.