To investigate the bacteria community and biodiversity of four-years pickled Yanshan Dongcai. We studied the bacterial communities of Dongcai by 16S rDNA diversity analysis and the cultured species isolated from Dongcai sample by Restriction Fragment Length Polymorphism (RFLP) and 16S rRNA gene sequence analysis. The 16S rDNA diversity showed that the bacteria belonged to the phyla Proteobacteria (87.9% ) and Firmicutes (7.1% ), including many moderately halophilic bacteria such as Virgibacillus kekensis, Marinococcus albus, Salinicoccus sp., Lactobacillus halophilus and Halomonas. Only 5% of clone sequences belonged to the phylum Actinobacteria. Thirty-five strains were isolated from Dongcai sample, and 16S rDNA-RFLP analysis indicated that 34 isolates affiliated with the phylum Firmicutes, including Virgibacillus, Bacillus megaterium and Gracilibacillus saliphilus which were moderately halophilic bacteria, but only one isolate belonged to the phylum Actinobacteria. The bacterial diversity is low in Dongcai, dominated by moderately halophilic bacteria.