The invention relates to a microorganism fermentation feed and a preparation method thereof. The fermentation feed comprises the following components: 400-600g of corn, 50-200g of bran, 150-250g of bean meal, 20-40g of cottonseed meal, 20-40g of rapeseed meal, 50-100g of puffed soybean meal, 20-40g of fish meal, 5g of tourmaline powder, 300-500g of pure drilled water and streptococcus acidi lactici fermented solution. The feed has the advantages of promoting animal growth, adjusting normal flora in gastrointestinal tracts, maintaining microflora balance, improving food true nutritive value and biological value, lowering serum cholesterol, controlling endotoxin, inhibiting putrefying bacteria from growth in intestinal tracts, enhancing organism immunity, having antagonistic effects on pathogenic bacterium such as dysentery bacillus, typhoid bacillus, Salmonellaparatyphi, Campylobacter, staphylococcus and the like, reducing culture cost and effectively putting antibiotics abuse to an end.