TECHNOLOGY FOCUS - BIOTECHNOLOGY - Preparation (claimed): The method for preparing the biological organic fertilizer fermenting strains comprises: (a) breeding seed: using the strains D1 and S4 as strains, breeding seed in a seed triangular bottle, adding culture medium MD in the seed triangular bottle; where the culture medium MD comprises (wt.%) glucose (0.7-1.0), peptone (0.6-0.8), yeast past (0.3-0.5), sodium chloride (NaCl) (0.2-0.4), potassium dihydrogen phosphate (KH2PO4) (0-0.2), and purified water (83-98); and the culture medium MD has pH value of 6.7-8.0; breeding the seed by inoculating slant starter to the culture medium after sterilizing; and oscillating for 16-22 hours at 28-30 degrees C; (b) amplifying: adding the culture medium MD into the fermenting tank; inoculating the culture medium in terms of 3-8% of culture medium MD in the fermenting tank by volume, mixing to obtain seed; where in amplifying, the pressure of tank is 0.4-0.6 MPa, the temperature of tank is 28-30 degrees C, the air flow is 0.3-0.6 (v/v/minute), the rotating speed of stirrer is 200 rotations/minute, and the amplifying duration is 18-24 hours; where the fermentation is stopped when the optical density (OD) value of the culture liquid is reduced by 0.02, which is 600 nm; (c) breeding product: adding culture medium MD into the large fermenting tank; sterilizing, inoculating amplified culture material in terms of 3-8% of culture medium MD in the fermenting tank by volume to obtain liquid seed; where in amplifying, the pressure of tank is 0.4-0.6 MPa, the temperature of tank is 28-30 degrees C, the air flow is 0.3-0.6 (v/v/minute), the rotating speed of stirrer is 140-200 rotations/minute, and the amplifying duration is 18-24 hours; where the fermentation is stopped when OD value of the culture liquid is reduced by 0.02, which is 600 nm; and (d) condensing the fermenting culture material by 1-8 times by filter, detecting to obtain liquid bacterium agent; or condensing the fermenting culture material by 1-8 times by filter, adding dispersant, and further drying to obtain solid bacterium agent. Preferred Composition: The strains are independently used or combined in use in the ratio of 1-4:1 of D1 strain to S4 strain.