The invention relates to the field of biotechnology, in particular to a DDGS fermented feed additive, fermented feed and a preparation method of the fermented feed. The DDGS fermented feed additive comprises a composite microbial strain, a medium temperature amylase and a strong base. The composite microbial strain comprises lactobacilli, bacillus subtilis, bacillus licheniformis and saccharomyces cerevisiae. DDGS is fermented by means of microorganisms, and crude fiber, non-starch polysaccharides and the like in the DDGS can be degraded through the metabolism of the microorganisms, so that the protein content is increased, and protein macromolecules are degraded into small peptides and other small easily-absorbed molecules; meanwhile, due to a large number of beneficial microorganisms propagated in the fermentation process, a large number of lactic acids and other organic acids generated in the fermentation process, and the environment with the lower pH value, molds in the DDGS can be inhibited; due to the lactic acids and the other organic acids generated in the fermentation process, the feed can have the fragrant and sweet taste, and the DDGS amount added in the feed is further increased.