The invention provides a water soluble fertilizer containing high-concentration humic acid. The water soluble fertilizer comprises, by weight, 15-25 parts of a water soluble humic acid salt, 18-25 parts of urea, 9-15 parts of dipotassium hydrogen phosphate, 8-13 parts of potassium acetate, 0.5-2 parts of borax, 0.1-10 parts of polyglutamic acid, 1-5 parts of rhamnolipid, 5-10 parts of a hydroxymethyl cellulose aqueous solution and 30-40 parts of water. The water soluble fertilizer has humic acid content greater than or equal to 150g / L. The invention also provides a preparation method of the water soluble fertilizer containing high-concentration humic acid. The preparation method comprises the following steps of 1, carrying out heating stirring of the water soluble humic acid salt and water to obtain a humic acid salt solution, 2, adding dipotassium hydrogen phosphate, potassium acetate, borax, polyglutamic acid, rhamnolipid and urea into the humic acid salt solution, and carrying out heating stirring to obtain a mixed solution, and 3, carrying out emulsification of the hydroxymethyl cellulose aqueous solution and the mixed solution to obtain the water soluble fertilizer containing high-concentration humic acid. The water soluble fertilizer has obvious fertilizer efficiency, is environmentally friendly, stable and uniform and has a wide application range.