The invention provides a low-temperature degradation straw composite microbial agent containing Saccharomyces cerevisiae. The composite bacterial agent uses 6 strains, so that the corn stalk maturitydays can be increased by 2 to 3 days in an environment with the outdoor temperature of 1 to 6 DEG C, and then the composite bacterial agent is particularly suitable for northern regions. Compared withthe control group, the average milk yield of cows fed with corn straw treated with compound bacteria is increased by 8.9kg, the content of crude fibers in cow manure is decreased by 3.4%, and the average daily intake is increased by 2.3kg, because the compound bacteria for degrading lignocelluloses is added, and a large amount of Saccharomyces cerevisiae is contained in the compound bacteria, thecorn straw has soft texture and acid aroma, and the palatability is obviously improved to increase the appetite of livestock. Furthermore, the Saccharomyces cerevisiae can promote animal growth, regulate normal gastrointestinal flora and maintain microecological balance, thereby having the effects of improving gastrointestinal functions, increasing food digestibility and biological values, reducing serum cholesterol, controlling endotoxin, inhibiting the growth of spoilage bacteria in intestinal tracts and improving the immunity of bodies and the like so as to further increase the daily output.