Abstract: In order to study the use of bacteria and moulds for different effects of mixed fermentation,the development of new co-fermentation technology,different inoculation methods were adopted in this study,3 samples of single strain fermentation and 4 mixed strains fermentation samples were obtained,the effect of different strains on the quality characteristics of fermented soybean was studied. Sample B was prepared by fermentation with Bacillus subtilis strains according to the method of Korean cheonggukjang,and samples A and M were prepared by Aspergillus oryzae and Mucor racemosus strains according to the fermentation method of fermented Douchi. AB,BA,MB and BM were respectively prepared in the fermentation samples of mixed strains according to the different inoculation sequence of the two strains. Reults showed that,The highest protease activity of sample B was(257.32±3.04) U/g between 0 and 9 aging days. The reducing sugar of sample M reached 1.17% on the first day of maturity,higher than other samples. The contents of A and MB were high,and the content of ammonium nitrogen was the highest in sample B. The pH of all samples showed a downward trend,while the titration acidity range increased from 0.02% to 0.19%. During the 9 aging days,the L^* value of each sample's chromaticity showed a continuous downward trend,and the phenomenon of MB Browning was obvious. In the 7 experimental groups,the samples of MB by mixed bacteria fermentation characteristics improve the quality of fermented soybean,verify the use of bacteria and moulds for co-fermentation technology can improve the quality of the fermented soybean features.