The invention discloses a special fertilizer for sweet potatoes. The special fertilizer is prepared from the following raw materials in parts by weight: 10-30 parts of chicken manure, 10-30 parts of pig manure, 5-15 parts of biochar, 5-15 parts of fly ash, 10-30 parts of anaerobic digestion sludge, 2-5 parts of an EM microbial agent, 2-8 parts of nitrogen fertilizers, 3-9 parts of phosphate fertilizers and 5-15 parts of potassium fertilizers. The special fertilizer well improves the soil for planting the sweet potatoes, improves the growth environment of the sweet potatoes and contributes to the growth of the sweet potatoes.