Abstract:Two-step fermentation were implemented as follows：Bacillus subtilis and Aspergillus niger aerobic fermentation were used as primary fermentation，then Saccharomyces cerevisiae and Lactobacillus bulgaricus anaerobic fermentation were used as secondary fermentation.The results showed that the percent conversion of peptide in the first step was 52.01%，the second step was 65.08%，additionally，the two-step fermentation was superior to one step fermentation.