Abstract: In this paper, the physical and chemical properties of swollen and normal vinegar were compared and analyzed. And the top gas composition of swollen vinegar was analyzed. Additional, several potential pollution microorganisms in swollen vinegar were separated and identified. Compared with normal vinegar, the results showed that total solids content increased by 65%, total acidity increased by 47.4% and amino nitrogen content increased 2.3 fold in swollen vinegar. And the gas composition in the top gas of swollen vinegar was mainly carbon dioxide. Six strains of bacteria were separated from swollen vinegar, and they were identified that No.1, No 2, RT-1, RT-2, RT-3, RT-4 were similar with Bacillus velezensis, Bacillus tequilensis, Bacillus velezensis, Staphylococcus saprophyticus.Staphylococcus capitis, Bacillus stubtilis, and the similarity was more than 98%. And each strain could produce white flocculation in sugar fermentation medium, in which No. 1 and No. 4 bacteria produced more precipitation. Among them, No. 4 bacteria could produce gas, which was the potential pollution microorganism causing vinegar swollen.