A water-soluble fertilizer. The invention belongs to the field of a crop fertilizer and specifically relates to a nano-scale multi-nutrient water-soluble fertilizer. The water-soluble fertilizer is composed of urea, monoammonium phosphate, potassium dihydrogen phosphate, Chinese medical stone, dolomite and other additives. The water-soluble fertilizer is prepared by the following steps: firstly micronizing Chinese medical stone and dolomite and carrying out water dissolution treatment, dissolving the mixture in water and simultaneously adding urea, monoammonium phosphate and potassium dihydrogen phosphate to be dissolved together, sending the mixture into a high pressure homogenizer for homogenization and refining to nanometers, adding the additives and mixing, concentrating and crystallizing, filtering and drying, crushing and packaging to obtain the nano-scale multi-nutrient water-soluble fertilizer. The water-soluble fertilizer has advantages of uniform color and granularity, adequate nutrient and fine particles and helps plants absorb nutrients. By the use of the water-soluble fertilizer, absorption and utilization of the fertilizer are raised for crops. Meanwhile, soil structure can be improved. Soil hardening is prevented, soil granulation is enhanced, microbial activity of plant roots is raised, and product quality of crops is promoted. The water-soluble fertilizer has good water solubility, is irrigated with water, will not block pipelines, and is suitable for integration of water and fertilizer.