NOVELTY - Preparing organic material-decomposing agent comprises preparing Bacillus subtilis raw powder by inoculating, carrying out fermentation, centrifuging, concentrating, transferring into a mixing tank, adding light calcium carbonate, stirring uniformly, passing into spray drying tower for drying and discharging powder, preparing Aspergillus oryzae and Saccharomyces cerevisiae raw powder by inoculating and fermenting, and uniformly mixing all the raw powders.    USE - The method is useful for preparing organic material-decomposing agent (claimed).    ADVANTAGE - The method has utilizes symbiosis strains without antagonistic effect, increases protease activity of product, enhances ability to antagonize crop pathogens and play bio-control promoting effect.    DETAILED DESCRIPTION - Preparing organic material-decomposing agent comprises: (i) preparing Bacillus subtilis including: (i.a) inoculating the laboratory stored Bacillus subtilis strain into a prepared conical flask under sterile environment, culturing at 31-32 degrees C for 31-35 hours, checking for contamination and reserving the pure culture as fermentation inoculum; (i.b) preparing fermentation culture medium by dissolving 20 g glucose, 15 g peptone, 5 g sodium chloride, 0.5 g beef extract and 20 g agar in water, making up to 1 l with water and transferring into fermentation tank; (i.c) inoculating 3 cm3 pure culture along with medium from conical flask into fermentation tank aseptically; (i.d) carrying out fermentation at 29-34 degrees C under rotating speed of 230 rotations/minute for 8 hours, determining sample every 4 hours between 8-24 hours and determining sample every 2 hours between 24-36 to ensure no contamination, and completing the culturing when spore rate reaches 90-95%; (i.e) centrifuging for 5-6 times and concentrating to obtain concentrated broth; and (i.f) transferring the concentrated broth into a mixing tank, adding 20-40 wt.% light calcium carbonate, stirring uniformly, passing into spray drying tower for drying with an air inlet temperature of 205-210 degrees C and an air outlet temperature of 80-82 degrees C, and discharging Bacillus subtilis raw powder having moisture content of 7-8% from the spray drying tower and whirlwind orifice, uniformly mixing, sealing and preserving; (ii) preparing Aspergillus oryzae including: (ii.a) preparing fermentation liquid by dissolving 50 wt.% wheat bran, 0.04 wt.% manganese sulfate, 0.4 wt.% calcium chloride, 0.2 wt.% potassium dihydrogen phosphate in proper amount of water; (ii.b) inoculating the laboratory stored Aspergillus oryzae strain into a prepared conical flask under sterile environment, culturing at 32-40 degrees C for 2-3 days under rotation condition of 230 rotations/minute, adding sterile water into the culture slant and making it spore suspension to obtain a concentration of 107 CFU/ml, inoculating the spore suspension into autoclaved shake flask medium in a ratio of 1:20 and culturing at 34 degrees C under 230 rotations/minute for 2 days; (ii.c) placing the culture in a strain culture room and culturing at 28 degrees C, cooling if temperature exceeds 30 degrees C via oxygen ventilation, fermenting for 68-72 hours to obtain culture medium full of spores; and (ii.d) drying the fermentation culture medium at 45 degrees C, controlling moisture content to more than 10% and crushing via crusher to obtain Aspergillus oryzae raw powder, sealing and preserving; (iii) preparing Saccharomyces cerevisiae including: (iii.a) inoculating the laboratory stored Saccharomyces cerevisiae strain into a prepared test tube slant under sterile environment, culturing at 33-37 degrees C for 42-48 hours, checking for contamination and reserving the pure culture as fermentation inoculum; (iii.b) preparing fermentation culture medium by dissolving 7 g white sugar, 1 g yeast extract, 0.8 g peptone, 10 g soybean flour and 0.5 g potassium dihydrogen phosphate in water, making up to 1 l with water and adding into fermentation tank; (iii.c) sterilizing and cooling fermentation tank via steam at 121 degrees C for 30 minutes under stirring, opening cooling system and cooling medium to 32-35 degrees C; (iii.d) inoculating 3 cm3 pure culture along with medium from conical flask into fermentation tank aseptically; (iii.e) carrying out fermentation at 33-37 degrees C for 8 hours by providing oxygen, determining sample every 4 hours between 8-24 hours and determining sample every 2 hours between 24-36 to ensure no contamination, and completing the culturing when the yeast attains stable budding stage; (iii.f) centrifuging for 5-6 times and concentrating to obtain concentrated broth; (i.g) transferring the concentrated broth into a mixing tank, adding 20-40 wt.% light calcium carbonate, stirring uniformly, passing into spray drying tower for drying with an air inlet temperature of 205-210 degrees C and an air outlet temperature of 80-82 degrees C, and discharging Saccharomyces cerevisiae raw powder having moisture content of 5-6% from the spray drying tower and whirlwind orifice, uniformly mixing, sealing and preserving; and (iii.h) preparing decomposing agent by uniformly mixing Bacillus subtilis raw powder, Aspergillus oryzae raw powder and Saccharomyces cerevisiae raw powder by controlling the content of Bacillus subtilis to 32000000000/g, Aspergillus oryzae to 3000000000/g and Saccharomyces cerevisiae to 30000000000/g, adding diatomite and mixing uniformly to obtain the product, where the product comprises 350 million/g Bacillus subtilis, 90 million/g Aspergillus oryzae and 160 million/g Saccharomyces cerevisiae.