The invention belongs to the field of fertilizers, and particularly relates to a tea polyphenol and humic acid water-soluble fertilizer and a preparation method thereof. Urea, ammonium nitrate phosphate, potassium dihydrogen phosphate, boron sulfate, potassium sulfate, ammonium sulfate, humic acid and tea polyphenols are mixed according to a certain proportion to obtain a composite water-soluble fertilizer, by the effect of reaction of the tea polyphenols and part of metal ions to generate precipitate, the humic acid is protected against reacting with calcium ions and magnesium ions in hard water to form precipitate, furthermore, by addition of ammonium bicarbonate, ph of the dissolved water-soluble fertilizer is suitable for reaction of the tea polyphenols. After the water-soluble fertilizer is dissolved in water, precipitate will appear, but the precipitate does not contain humic acid basically, clear liquid is used for fertilizing, the rest suspension is irrigated on the earth's surface, the utilization rate of the humic acid can be increased, and furthermore, plant diseases and insect pests can be inhibited to a certain degree.