The invention discloses a microbial fermentation antibiotic-free feed, which comprises a batch and a composite fermentation material. The batch consists of the following raw materials in part by weight: 30 to 50 parts of corn, 20 to 40 parts of bean pulp, 5 to 20 parts of cotton seed meal, 2 to 5 parts of calcium hydrophosphate, 0.2 to 0.4 part of salt, 0.1 to 0.2 part of composite trace element, and 0.2 to 0.4 part of composite vitamin; and the composite fermentation material consists of the following fermentation materials in part by weight: 30 to 70 parts of lactobacillus acidophilus fermentation material, 10 to 20 parts of bacillus subtilis fermentation material, 20 to 35 parts of saccharomyces cerevisiae fermentation material, 1 to 3 parts of trichoderma longbrachiatum fermentation material, 1 to 3 parts of aspergillus niger fermentation material, and 1 to 3 parts of aspergillus oryzae fermentation material, wherein the weight ratio of the batch to the composite fermentation material is 96-92:4-8.