Abstract: The diversity of bacteria or fungus during the fermentation process of salted leaf mustard ( Brassica juncea) was studied by Polymerase Chain Reaction-Denaturing Gradient Gel Electrophoresis ( or PCR-DGGE, for short) in the text. The result showed: during the whole fermentation process of pickled leaf mustard, there were some bacteria that included Halomonas sp., Marinilactibacillus psychrotolerans, Lactobacillus kimchii, Chromohalobacter sp., Uncultured bacterium and Uncultured Halomonas sp.; and there were some fungi that included Saccharomyces cerevisiae, Rhodotorula mucilaginosa, Aspergillus niger, Debaryomyces hansenii, Candida sp. and Uncultured fungus. But there was Psychrobacter sp. that only existed in the initial stage of fermentation. Furthermore, the quantity of Halomonas sp., Marinilactibacillus psychrotolerans, Saccharomyces cerevisiae or Rhodotorula mucilaginosa changed little, and the four microbe were the dominant strains of the pickled leaf mustard.