The invention discloses a synergist of a functional fertilizer, comprising the following raw materials by weight: 0-150 portions of compound amino acid, 0-24 portions of plant growth regulator, 0-18 portions of synergistic sodium, 0-18 portions of a-nafusaku, 0-3 portions of antidote, 0-4 portions of pesticide, 0-600 portions of magnesium sulfate, 0-600 portions of nano calcium, 0-10 portions of zinc sulfate, 0-5 portions of ammonium molybdate, 0-15 portions of boric acid, 0-364 portions of adsorbent and 193-800 portions of bond. The preparation method comprises the following steps according to three proportions: adding water for mixing, rubbing, cutting, pelletizing, polishing, drying, cooling and screening, and then mixing the screened products with particle diameter less than 1 mm madeby three different proportions after equal part measuring by a computer, measuring, packaging and obtaining products. The invention can be used after mixing with a normal fertilizer easily and is suitable for various crops and soils, climates and different ways of fertilizing, thereby reducing the use level of the fertilizer and improving the utility ratio of the fertilizer. The invention has theadvantages of low use level, quick returns, stable fertilizer effect and long duration.