The invention discloses a flower special fertilizer and a preparation method thereof. The fertilizer comprises the following raw materials by weight: 1-4 parts of ammonium hydrogen carbonate, 30-35 parts of mushroom residue, 10-20 parts of potassium humate, 40-50 parts of chicken manure, 3-8 parts of carboxymethyl chitosan, 6-12 parts of ammonium chloride, 1-5 parts of ferrous sulfate, 10-20 parts of peat soil, 6-10 parts of rice bran, 4-8 parts of wheat bran, 5-10 parts of fallen leaves, 10-15 parts of feathers, 20-40 parts of straw, 12-15 parts of ammonium phosphate, 10-25 parts of urea, 6-10 parts of potassium sulfate, 6-10 parts of ammonium sulfate, 4-6 parts of azadirachtin, 2-8 parts of zinc sulfate, 2-6 parts of borax and 2-5 parts of microbial ferment. The fertilizer provided by the invention has scientific and reasonable formula, high nitrogen, phosphorus and potassium content, double effects of fertilization and insecticide, and is environment-friendly, pollution-free, and conducive to protection of ecological environment and soil structure.