Abstract: Distiller's grains serve as the important by-products in ethanol production, particularly on white spirits in China. Normally, the key grain can be processed in a solid-state fermentation, thereby to distill a mixture of grains and bran husks. After the processing, the distiller's grains can be remained readily available rich in organic matter, such as cellulose and protein. China can produce about 30 million tons of distiller's grains every year, as the consumption of white spirits increases. The discarded distiller's grains have become the waste of raw materials, further to pollute the environment, due to the lack of effective treatment methods. It is necessary to explore much more efficient disposal of distiller's grains. This study aims to explore the decomposition of distiller's grains, in order to obtain microorganisms with strong capacity of cellulose degradation in distillates. 39 strains of bacteria were isolated from in Chinese maotai-flavor fermented grains, Chinese mild-flavor fermented grains, Chinese strong-flavor Daqu starter and the soil of bamboo forest, using sodium carboxymethyl cellulose as the only carbon source. Six strains were quantitatively screened using Congo red staining and filter paper strip disintegration experiments for qualitative preliminary screening, combined with the endoglucanase, exoglucanase, and β-glucosidase enzyme activities produced by the strains. Based on morphological, physiological, biochemical, and molecular biological characterization, six cellulase-producing bacteria were identified as Bacillus licheniformis, Paenibacillus taichungensis, Bacillus amyloliquefaciens, and Bacillus subtilis, Sphingobacterium thalpophilum, Streptomyces phaeochromogenes. The optimum lees cellulose-degrading strain was further determined the B2 strain (Bacillus subtilis) in the tests of pH, temperature, and alcohol stress. Specifically, Bacillus subtilis B2 strain has demonstrated a good tolerance, while grew well in an environment of pH value 3.0, at the temperature of 44 ℃, and the alcohol content of 4% by volume. According to the single-factor test, a Box-Benhnken response surface method was used to optimize the processing parameters in the treatments. The optimal process conditions were determined to be 71 g/L distiller's grains, the temperature of 37 ℃, pH value 6.4, and the inoculation size of 8%, for the degradation of distiller's grains. In addition, the degradation rate of distiller's grains can reach 15.23% in this case. The findings demonstrated that the selected Bacillus subtilis can effectively decompose distiller's grains, and thereby be expected to provide a promising application potential in the disposal of distiller's grains.