The invention discloses a fulvic acid macro-element water-soluble fertilizer and a preparation method thereof. The fertilizer is composed of the raw materials of, by weight: 40-50 parts of potassium sulfate, 20-30 parts of ammonium sulfate, 3-5 parts of urea, 10-15 parts of monoammonium phosphate, 15-20 parts of potassium fulvate, 2-3 parts of zinc sulfate, 2-3 parts of boric acid, 1-2 parts of a soil improving agent, 0.5-1 part of a plant growth regulator ND-6, and 0.5-1 parts of naphthylacetic acid. The fertilizer has the characteristics of full nutrition, full water solubility, no pollution, and sterilizing property. The fertilizer contains NPK macro-elements sulfur, calcium, magnesium, zinc, boron, and the like needed by plants, potassium fulvate with a chealation effect, and the plant growth regulator. The fertilizer has the advantages of fast absorption, high efficiency, high quality, water saving, and significant yield increase. With the fertilizer, growth and reproduction of harmful microbes such as soil nematode can be inhibited, soil-source pest and disease can be reduced, and crop disease resistance can be improved.