The invention discloses a mulberry foliage fertilizer and a preparation method thereof. The mulberry foliage fertilizer comprises the following raw materials in parts by weight: 10-12 parts of urea, 3-4 parts of zinc sulfate, 4-6 parts of sodium selenite, 2-4 parts of EDTA (Ethylene Diamine Tetraacetic Acid) chelated iron, 5-6 parts of compound amino acids, 4-5 parts of sarcandra glabra, 2-4 parts of ash bark, 6-8 parts of garden radish leaf, 4-6 parts of castor leaves, 1.5-2.5 parts of citric acid, 2.5-3.5 parts of copper sulfate, 3-4 parts of brassinolide, 8-10 parts of calcium superphosphate, 2-4 parts of ferrous sulfate, 1-2 parts of ammonium dihydrogen phosphate and 5-6 parts of wood vinegar. The mulberry foliage fertilizer disclosed by the invention is comprehensive in nutrition and enriched in various nutrient elements needed by mulberries, so that the mulberries can rapidly obtain the nutrition, and the yield and quality of mulberry fruits and mulberry leaves are improved. Meanwhile, the mulberry foliage fertilizer disclosed by the invention has excellent insecticidal performance, is capable of reducing plant diseases and insect pests of the mulberries and achieves the effects of increasing both production and income.