NOVELTY - A water-soluble synergistic compound fertilizer composition comprises polymer gel formed from inorganic fine particles containing following components: 50-60 pts. wt. of inorganic substrate, 25-30 pts. wt. of carboxylic acid, 5-15 pts. wt. of amide material, 3-5 pts. wt. catalyst, 1-3 pts. wt. of thickening agent and 0.5-1 pts. wt. amino acid compound. The inorganic substrate is e.g. silicon adhesive or lithium magnesium silicate. The carboxylic acid is monocarboxylic acid or dicarboxylic acid, where monocarboxylic acid is e.g. benzoic acid and dicarboxylic acid is e.g. succinic acid.    USE - As water-soluble synergistic compound fertilizer composition (claimed).    ADVANTAGE - The composition can quickly disperse fine gel particles in water, has chelating absorption effect, can absorb various nutrients in chemical fertilizer, provides local microcirculation system, promotes plants to absorb nutrients, prevents nutrient loss, and greatly improves fertilizing effect of composite fertilizer composition. The agent has high absorption rate, is convenient to use, does not form residue, provides environmental protection, avoids shortage of water resources, has obvious water-saving effect, disperses easily in water, has large absorbing capacity, increases utilization ratio of fertilizer, and avoids environmental pollution.    DETAILED DESCRIPTION - A water-soluble synergistic compound fertilizer composition comprises polymer gel formed from inorganic fine particles containing following components: 50-60 pts. wt. of inorganic substrate, 25-30 pts. wt. of carboxylic acid, 5-15 pts. wt. of amide material, 3-5 pts. wt. of catalyst, 1-3 pts. wt. of thickening agent, and 0.5-1 pts. wt. of amino acid compound. The inorganic substrate is at least one of silicon adhesive, kaolin, attapulgite, diatomaceous earth, sodium bentonite, or lithium magnesium silicate. The carboxylic acid is one of monocarboxylic acid or dicarboxylic acid, where the monocarboxylic acid is benzoic acid, acetic acid, propionic acid, methane sulfonic acid, or para-nitrobenzoic acid and the dicarboxylic acid is at least one of succinic acid, glutaric acid, adipic acid, decanedioic acid, suberic acid, azelaic acid, sebacic acid, tartaric acid, or malic acid. The amide material is at least one of urea, formamide or acetamide. The catalyst is at least one of sodium thiosulfate, sodium bisulfite, potassium bisulfite, or sodium sulfite. The thickening agent is at least one of cyclodextrin, hydroxypropyl methyl cellulose or acrylamide. The amino acid compound is 1,2-diamino-ethane-tetraacetic acid, ethylenediamine disuccinic acid, diethylene triamine pentaacetic acid, or hydroxy ethylene diamine triacetic acid. An INDEPENDENT CLAIM is included for preparation of the composition involving taking 50-60 pts. wt. of inorganic substrate, stirring by microwave oscillation and forming into suspension having concentration of 10-20%, then adding phosphate and dispersing for 20-30 minutes, where the phosphate is sodium hexametaphosphate, trimeric sodium phosphate, or sodium pyrophosphate, where the adding amount of inorganic substrate is 0.2-0.5%; heating the suspension at 60-80 degrees C, and mixing with 25-30 pts. wt. of carboxylic acid, stirring, subjecting to acidification process for l-2 hours, and then maturating for 24-48 hours; after acidifying, mixing with 5-15 pts. wt. of amide material, 3-5 pts. wt. of catalyst and subjecting to polymerization in reaction kettle, where reaction conditions in the kettle are as follows: pressure is 5-7 MPa, temperature is 80-100 degrees C, stirring speed is 100 to 200 rpm, stirring reaction time is 30-60 minutes; polymerizing the inorganic substrate and the amide material to form inorganic polyaminocarboxylic acid material, and then filtering; adding 1-3 pts. wt. of thickening agent, and 0.5-1 pts. wt. of amino acid compounds and then mixing with the inorganic polyaminocarboxylic acid material, coating with dispersing material in a dispersing machine, dispersing and rotating at a speed of 1000-1200 rpm, controlling dispersion time at 3-5 minutes by mechanical-chemical force; and adhering thickening agent and the amino acid compound to the inorganic polyaminocarboxylic acid material particle surface to form the composition.