The invention discloses organic water-soluble fertilizer and a preparation method. The organic water-soluble fertilizer is prepared from the following raw materials in parts by weight: 50-60 parts of lactic acid fermentation residues, 45-55 parts of amino acid, 20-30 parts of humic acid, 30-40 parts of ammonium dihydrogen phosphate, 40-50 parts of potassium nitrate, 20-30 parts of urea, 30-50 parts of calcium carbonate powder, 6-8 parts of glucose, 20-30 parts of starch, 3-5 parts of alginic acid, 13-16 parts of hydroxyethylcellulose, 3-6 parts of hydrogen peroxide, 2-6 parts of sodium stearate, 10-14 parts of bentonite, 6-9 parts of styrene, 13-16 parts of methacrylic acid, 3-4 parts of dimethyl formamide, 8-12 parts of astragalus polysaccharide, 4-8 parts of hypericin, 5-7 parts of hydroxyethyl cellulose, 3-5 parts of potassium fulvate and 60-75 parts of water. The organic water-soluble fertilizer has the advantages that soil organic matter can be increased, and emission of greenhouse gas is reduced; soil fertility is improved; the carbon and nitrogen ratio of soil is increased, and number and breeding of beneficial microorganisms are increased; soil permeability is improved, soil microbial flora is increased, and soil is improved; the soil pH is adjusted; heavy metals and pesticide residues in soil can be adsorbed and passivated, and damaged soil is remedied.