Abstract: In order to find out the dynamic changes of microbial diversity, physical and chemical indicators in the fermented Paocai, the microorganisms in the Paocai brine of each generation were isolated and identified by culturing method and the total acid, pH, nitrite, organic acids and other physical and chemical indicators were detected. The results showed that lactic acid bacterial and yeast were the dominant bacteria and fungi in the Paocai brine respectively. L.pentosus, L. plantarum, L. brevis and L. citreum were main lactic acid. K. exigua, P. membranifaciens, C. tropicalis and P. kudriavzevii were main yeast. The nitrite content of multi-generated fermented Paocai and brine decreased gradually, reaching 0.63-0.81 mg/kg in the later period, which was much lower than 20 mg/kg of nitrite in Chinese Paocai products. The total acid in the multi-generational fermented Paocai brine showed an increased trend from 0.58 g/dL to 0.9 g/dL in the last generation. There are abundant organic acids, organic acid salts in Paocai brine. Organic acids in Paocai brine mainly include tartaric acid, succinic acid, acetic acid and lactic acid. Lactic acid and acetic acid increased and accumulated with the increase of fermentation algebra. Finally they remained basically stable in the later period. The results revealed that the microorganisms and physicochemical basically remained steady in the later period in the multi-generational fermented paocai brine. The results of this study can provide data reference to guide the traditional Paocai industrialization.