NOVELTY - Decomposing agent comprises Bacillus sp. N8 strain, Streptomycete sp. F2 strain and Penicillium oxalicum strain have preservation number CCTCC NO: M2014464, CCTCC NO: M2014465 and CCTCC NO: M2014466 respectively.    USE - Decomposing agent used for fermenting material bed for preparing organic fertilizer (all claimed).    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for:    (1) a method for preparing decomposing agent, which involves inoculating Bacillus sp. in a seed culture medium and then culturing at 40-45 degrees C for 24-36 hours to obtain seed culture, where seed culture medium comprises tryptone, yeast extract, sodium chloride, agar and medlar, inoculating seed culture into fermentation culture medium and then culturing at 40-45 degrees C to obtain Bacillus sp. fermentation culture, where fermentation culture medium comprises glucose, bean cake powder, manganese sulfate, yeast powder, ferric chloride, potassium dihydrogen phosphate, calcium carbonate, magnesium sulfate and water, inoculating Streptomycete sp. in a seed culture medium and then culturing at 40-45 degrees C for 2-3 days to obtain seed culture, where seed culture medium comprises soluble starch, potassium nitrate, sodium chloride, potassium diammonium phosphate, magnesium sulfate, ferrous sulfate and agar, inoculating seed culture into fermentation culture medium and then culturing at 40-45 degrees C to obtain Streptomycete sp. fermentation culture, where fermentation culture medium comprises yeast extract, soluble starch, maltose, and cobalt chloride, inoculating Penicillium oxalicum in a seed culture medium and then culturing at 30-35 degrees C for 2-3 days to obtain seed culture, where seed culture medium comprises potato and glucose, inoculating seed culture into fermentation culture medium and then culturing at 28-30 degrees C for 5-7 days to obtain Penicillium oxalicum fermentation culture, where fermentation culture medium comprises corn powder, bran, inorganic salt liquid, ammonium sulfate and magnesium sulfate, mixing all cultures to obtain the decomposing agent;    (2) a method for preparing organic fertilizer involves drying chicken manure, peat and phosphoric acid and then mixing to obtain material bed; and    (3) fermenting material using decomposing agent to obtain the fertilizer.