The invention discloses a water soluble fertilizer with herbicidal activity. The water soluble fertilizer with the herbicidal activity comprises the following components in parts by weight: 100-150 parts of nitrogen-potassium fertilizer, 30-50 parts of biostimulant, 8-12 parts of a surfactant and 3-5 parts of an anti-blocking agent in parts by weight, wherein the biostimulant comprises bacillus subtilis (Bacillus Subtilis) LTBS01 and has been preserved in China Center for Type Culture Collection; and the preservation number is CCTCCNO: M2018246. The water soluble fertilizer with the herbicidalactivity, disclosed by the invention, is a functional water soluble fertilizer, can be used as a pure nutritional type water soluble fertilizer to provide nutrition for fruit trees, can also be usedas a herbicide to prevent and treat orchard weeds, does not contain any the herbicide and pesticide ingredients, has the characteristics of pesticide and fertilizer combination, high fertilizer efficiency, stable pesticide effect, safety and no chemical injury and is an efficient, pollution-free, green and environmentally friendly novel functional fertilizer. The invention discloses a method for preparing the water soluble fertilizer with the herbicidal activity into a solid powder preparation. The method for preparing the water soluble fertilizer with the herbicidal activity into the solid powder preparation, disclosed by the invention, has the advantages that the method is simple, industrial production is easy to realize, and the product quality is stable.