NOVELTY - Microbial straw decomposition agent comprises cellulase preparation, greater than or equal to 0.4x 106 colony forming unit (CFU)/g white rot fungus, greater than or equal to 0.2x 106 CFU/g Bacillus subtilis, greater than or equal to 0.2x 106 CFU/g Thermobifida fusca, greater than or equal to 0.2x 106 CFU/g B.pumilus and greater than or equal to 0.2x 106 CFU/g Saccharomyces cerevisiae as a production strain.    USE - The microbial straw decomposition agent in form of powder (claimed) is useful for controlling sclerotial blight, rice blast, wheat root rot and strawberry grey mold.    ADVANTAGE - The agent is prepared rapidly, conveniently and cost-effectively.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for method for preparing the microbial straw decomposition agent, which involves (a) performing solid fermentation using mixture of Trichoderma and Aspergillus, drying and crushing to obtain cellulase preparation, (b) inoculating white rot fungus in a fermentation culture medium, performing primary fermentation using fermentation broth at 30-35 degrees C for 2-3 days under condition of stirring for 2-3 times each day and secondary fermentation using solid medium at 30-35 degrees C for 8-10 days under condition of stirring for 5-10 times each day, after fermenting, adding 10-15 times adsorbent to substrate, drying and crushing into powder, where the weight ratio of culture medium in the primary fermentation and secondary fermentation is 1:5-10, (c) incubating original strain of B.subtilis, obtaining seed culture, inoculating in a fermentation tank, fermenting, centrifuging the fermentation broth, then adding adsorbent, drying and crushing to obtain B.subtilis powder, (d) incubating original strain of T.fusca, obtaining seed culture, inoculating in a fermentation tank, fermenting, centrifuging the fermentation broth, then adding adsorbent, drying and crushing to obtain T.fusca powder, (e) preparing B.pumilus seed culture medium and fermentation culture medium using 3 g beef extract, 10 g peptone, 10 g sodium chloride and 100 ml distilled water, inoculating the B.pumilus in the seed culture medium, culturing for 2 days, then inoculating in a fermentation tank containing fermentation culture medium, adding 40 volume/weight% wheat bran, adding the adsorbent, vacuum-drying, and crushing to obtain B.pumilus powder, (f) inoculating S.cerevisiae in a seed culture medium, culturing at 30 degrees C for 2 days, inoculating 8% seed culture in the fermentation tank containing fermentation culture medium, adding 10-15 times adsorbent to the substrate, drying and crushing to obtain S.cerevisiae powder, and (g) mixing the above-obtained powders, and obtaining product. The adsorbent is chosen from peat, zeolite powder, bentonite and calcium carbonate. The solid fermentation culture medium for comprises 50-80 wt.% bran, 25-40 wt.% straw powder, 5 wt.% ammonium sulfate, 5 wt.% potassium dihydrogen phosphate, 5 wt.% calcium carbonate, 0.1 wt.% magnesium sulfate, 0.1 wt.% calcium chloride, and 0.1-1 wt.% sodium chloride. The fermentation broth for white rot fungus comprises 20 g/l glucose, 15 g/l sucrose, 2 g/l yeast powder, 1.5 g/l potassium dihydrogen phosphate, 0.5 mg/l magnesium sulfate heptahydrate and 4 mg/l vitamin B1. The solid medium for white rot fungus comprises 10-30 wt.% wheat bran, 10-30 wt.% straw powder, 35-55 wt.% peanut powder, 5 wt.% bean cake powder, 0.1-2 wt.% urea, 0.1-0.5 wt.% dipotassium hydrogen phosphate, 0.1-0.5 wt.% magnesium sulfate and water (suitable quantity). The seed culture medium for B.subtilis comprises 10 wt.% corn meal, 0.5-3 wt.% peptone, 0.5-3 wt.% bean cake powder and 0.1-1 wt.% urea. The fermentation tank culture medium for B.subtilis comprises 2-8% corn powder, 0.5-3% peptone, 0.5-5% bean cake powder, 0.1-1% urea and 0.1-1% dipotassium hydrogen phosphate. The seed culture medium and fermentation culture medium (pH 7.2) comprise 10 g peptone, 5 g yeast extract, 5 g beef extract, 10 g sodium carboxymethyl cellulose (CMC-Na), and 100 ml distilled water.