Abstract: In this study,three acid-producing bacterias of Acetobactor pasteurianus BCP0454,Lactobacillus brevis BCP0738,Bacillus subtilis BCP0449 were isolated and purified from the fermentation process of Shanxi aged vinegar. The strains were identified from the aspects of morphological identification and molecular biology identification. The organic acids and flavor substances in the fermentation broth of the strains were investigated by high performance liquid chromatography and gas chromatography-mass spectrometry. The results showed that BCP0454 had a good ability to produce organic acids,and the content of acetic acid was relatively high,reaching to 4885.25 mg/100 mL. 17 kinds of flavor substances were produced. And the content of carboxylic acids and carbonyl compounds had accounted for a large proportion. BCP0738 could produce lactic acid and acetic acid at the same time,with a total amount of 1225.79 mg/100 mL. It could produce 23 kinds of flavor substances. The highest content of ester was 51.70%,and one kind of pyrazine could be produced. BCP0449 could produce 2 kinds of organic acids with the total amount of 2108.24 mg/100 mL. The content of ethyloin was 33.55 μg/100 mL,and 3 kinds of pyrazines could be produced at the same time.