NOVELTY - A composite microorganism fertilizer comprises 0.8-1 pts. wt. Bacillus amyloliquefaciens, 0.6-0.8 pts. wt. Bacillus thuringiensis, 0.5-0.7 pts. wt. Bacillus subtilis, 0.4-0.8 pts. wt. lactic acid bacteria, 1-3 pts. wt. fermenting agent, 30-35 pts. wt. corn straw, 20-30 pts. wt. grass carbon, 30-36 pts. wt. fly ash, 10-20 pts. wt. mushroom residues, 30-40 pts. wt. swelling pig manure, 2-4 pts. wt. methyl synergistic phosphorus powder, 1-3 pts. wt. synergistic ether powder, 0.4-0.6 pts. wt. ethylene, urea, diammonium phosphate and potassium sulfate.    USE - Composite microorganism fertilizer for controlling celery soft rot disease.    ADVANTAGE - The composite microorganism fertilizer reduces morbidity of the celery soft rot, enhances celery growth, increases celery yield, improves quality, increases probiotic bacteria in the soil and improves soil condition.    DETAILED DESCRIPTION - A composite microorganism fertilizer comprises 0.8-1 pts. wt. Bacillus amyloliquefaciens, 0.6-0.8 pts. wt. Bacillus thuringiensis, 0.5-0.7 pts. wt. Bacillus subtilis, 0.4-0.8 pts. wt. lactic acid bacteria, 1-3 pts. wt. fermenting agent, 30-35 pts. wt. corn straw, 20-30 pts. wt. grass carbon, 30-36 pts. wt. fly ash, 10-20 pts. wt. mushroom residues, 30-40 pts. wt. swelling pig manure, 2-4 pts. wt. methyl synergistic phosphorus powder, 1-3 pts. wt. synergistic ether powder, 0.4-0.6 pts. wt. ethylene, 12-16 pts. wt. urea, 10-12 pts. wt. diammonium phosphate and 6-8 pts. wt. potassium sulfate. An INDEPENDENT CLAIM is also included for a method for preparing a composite microorganism fertilizer, which involves culturing microorganism by inoculating Bacillus amyloliquefaciens, Bacillus thuringiensis, Bacillus subtilis and lactic acid bacteria to a culture medium, controlling fermentation conditions, preparing bacteria solution, finishing fermentation after 6-8 days, fermenting substrate by a mixture of corn straw, grass carbon, fly ash and dregs, controlling temperature, mixing urea, diammonium phosphate, potassium sulfate, methyl synergistic phosphorus powder, synergistic ether powder and ethylene, adding water to dissolve, obtaining a mixed material, drying and crushing to obtain the finished product.