The invention discloses a preparation method of flower fertilizer. Water, a boron source, zinc gluconate, xylitol, wax gourd stems, polyglutamic acid, matsutake residues, furfural residues, lac powder, buckwheat hull, palm leaves, wood vinegar, wild chrysanthemum stalk, horse manure and rabbit dung are weighed; the adverse resistance of crops is increased by 65%-85%, pollen germination and growth of pollen tubes are affected, development of propagative organs of plants is promoted, the problems that plants only blossom, but do not bear fruits are solved, an irreplaceable role is played in blossoming and fruit retention, 75%-95% of water is saved, nutrients are balanced, nutrition is reserved for growth of the plants in the next year, the number of beneficial microorganisms in the soil is increased by 60%-70%, metabolism, growth and development of the plants are influenced, protein is supplemented, chlorophyll is synthesized, apple bitter pit, pit spot and water core are prevented, fruit cracking of bagged fruits, black heart of pears and the like are reduced, the fruit quality is improved, and the storage period is prolonged.