Growth-promoting stable and synergistic water soluble fertilizer

The invention relates to a water soluble fertilizer and a preparation method, in particular to a growth-promoting stable and synergistic water soluble fertilizer and a preparation method. The water soluble fertilizer comprises the following components in percentage by weight: 10-50 percent of urea, 10-40 percent of ammonium nitrogen fertilizer, 10-30 percent of water soluble phosphorous fertilizer, 15-30 percent of water soluble potassium fertilizer, 0.5-10.0 percent of water soluble secondary elements, 0.1-8.0 percent of water soluble trace elements, 0.1-3 percent of fertilizer synergist, 0.01-10.0 percent of plant growth promoter, 0.01-10.0 percent of nitrogen stabilizer and 0-10 percent of water soluble additive, wherein the water soluble additive is a water soluble amino acid chelate and/or water soluble humic acid. The utilization ratio of the fertilizer can be increased by 60-100 percent compared with the conventional ordinary water soluble fertilizer, and the fertilizer effect can last for 120 days in maximum. Compared with an ordinary water soluble fertilizer, the growth-promoting stable and synergistic water soluble fertilizer has the advantages that the crop yield is increased by 20-60 percent by applying the same amount of fertilizer; the fertilizer can be saved by 20-40 percent at the same yield.