The invention discloses a compound probiotics preparation for biological organic fertilizers and a preparation method thereof. The preparation method comprises the following steps: performing activated culture of 14 kinds of probiotics, including Pseudomona putida, Streptomyces violovariabilis, Rhizobium sp., Azotobacter chroococcum, Bacillus subtilis, Bacillus amyloliquefaciens, Bacillus cereus, Bacillus subtilis, Bacillus weihenstephanensis, Bacillus mucilaginosus, Bacillus thuringiensis, Saccharomyces rouxii, Streptomyces griseus var. ferrugineus, and Streptomyces microflavus; performing mixed inoculation at a proportion of 1% to 5% to a 500 mL liquid seed culture medium; then performing amplification culture; and finally delivering the strains to a 500 mL fermentor and fermenting for 3 to 5 days under such conditions that the temperature ranges from 28 DEG C to 30 DEG C and the rotational speed is 200 rpm, to obtain a liquid-state compound probiotics preparation. The compound probiotics preparation for biological organic fertilizers, provided by the invention, plays important roles of taking advantage of microbial ecology, improving soil, promoting plant growth, improving the yield and disease resistance of crops and reducing the consumption of fertilizers.