showed that the levels of peptide with MW less than 1000 Da in the samples fermented by L. casei Zhang mixed with B. subtilis natto, L. plantarum P-8 mixed with B. subtilis natto for 24 h increased 5.0% and 12.9%. The sample fermented by B. animalis 937 mixed with B. subtilis natto decreased 4.6% relative to that of the control group, because the production of proteases was poor at the initial stage of the fermentation, the protein of the soybean was only partly hydrolyzed and the most peptides were utilized by B. animalis. The levels of peptide with MW more than 10,000 Da (Fig. 6) in the samples decreased 14.5% (B. animalis 937 with B. subtilis natto), 20.5% (L. plantarum P-8 with B. subtilis natto) and 22.3% (L. casei Zhang with B. subtilis natto) with the hydrolysis of proteases