The invention provides a compound microbiological preparation for fermenting soybean meal. The compound microbiological preparation contains the following components: lactobacillus plantarum with content not lower than 1*109/ml, lactobacillus acidophilus with content not lower than 5*108/ml, butyric acid bacteria with content not lower than 1*108/ml, and candida utilis with content not lower than 5*108/ml. The compound microbiological preparation can be used for inhabiting the growth and propagation of harmful bacteria such as pathogenic escherichia coli and salmonella in the fermentation process of soybean meal for a feed, effectively reducing the content of anti-nutritional factors in the soybean meal for the feed and the content of antigen proteins and bad oligosaccharide, and enhancing the digestibility of the soybean meal for the feed. The compound microbiological preparation has the advantages of safety, high efficiency, specificity, no residue, no side effect, and the like.