The invention discloses a novel soil microbial modifier and a preparation method thereof. The novel microbial improver comprises the following raw materials: attapulgite, weathered coal, edible fungusresidues, rice husks, earthworm feces, sawdust, slaked lime, activated carbon, molasses, wheat bran, soybean meal, a microbial composite bacterial agent and trace elements, wherein the microbial composite bacterial agent is composed of bacillus mucilaginosus, azotobacter chroococcum, bacillus laterosporus, bacillus amyloliquefaciens, yeast and lactobacillus plantarum. The soil microbial modifierprovided by the invention has a reasonable formula, has the effects of dissolving phosphorus, releasing potassium and fixing nitrogen, significantly promotes absorption and transformation of nitrogen,phosphorus and potassium by plants, increases the water permeability and water retention of the soil, reduces incidence of pests and diseases, reduces the heavy metal content in the soil, improves the acidity and alkalinity of the soil and promotes plant growth and development. Through tests, the use of the soil microbial modifier disclosed by the present invention can significantly increase theyield of crops, reduce the incidence of pests and diseases, and shorten the growth cycle of the crops.