An organic-inorganic microbiological water-soluble fertilizer specially used for grape is prepared from following raw materials: potassium fulvate, potassium nitrate, urea, monoammonium phosphate, polyaspartic acid, potassium sulfate, zinc sulfate, ferrous sulfate, borax, a microbiological preparation, copper sulfate, manganese sulfate and EDTA. A preparation method of the fertilizer includes following steps: mixing powdery potassium fulvate, the powdery microbiological preparation and powdery polyaspartic acid uniformly to obtain a mixed material; processing the mixed material at constant temperature to obtain a material A; respectively crushing the urea, the potassium nitrate, the potassium sulfate and the monoammonium phosphate with mixing uniformly to obtain a material B; crushing the zinc sulfate, the manganese sulfate, the ferrous sulfate, the borax, the copper sulfate and the EDTA with mixing uniformly to obtain a material C; mixing uniformly the material A, the material B and the material C to obtain a product. The fertilizer is complete in nutrition, is reasonable in formula, allows crops to absorb easily, has a significant yield-increasing effect, contains organic substances, inorganic substances, bacteria and medium-and-trace elements, is environmental-protective and is free of pollution, and can protect ecological environment and improve farmland soil.