Douchi is a Chinese traditional fermented food of soybean. In this study, the cooked soybean fermented by Multi-strains (Aspergillus oryzae and Aspergillus niger), traditional method and pure Aspergillus oryzae were analyzed and compared for volatile compound by GC-MS, using the simultaneous distillation and solvent extraction (SDE) combined technique, a total of 152 volatile compounds including 30 hydrocarbons, 21 alcohols, 8 aldehydes, 33 esters, 7 ketones, 6 phenols, 18 acids, 20 heterocyclic compounds, 3 sulfo compounds and 6 other compounds were identified. Results showed that the Multi-strains fermented samples had higher contents of volatile compounds than the pure Aspergillus oryzae inoculated samples. The predominant volatile compounds in Aspergillus oryzae and Aspergillus niger fermented soybeans included alcohols, acids, esters and pyrazines, and the major volatile compounds in the pure Aspergillus oryzae fermented soybean included hydrocarbons, aldehydes, acids and alcohols. Multi-strains fermented douchi has the most volatile compounds of the naturally fermented douchi.