Abstract: The microbial community diversity, the related characters and its flavor components were investigated during fermentation process of pickled amaranth stem using 16S rDNA clone library and GC-MS analysis methods. Results showed that Lactobacillu, Pediococcus and Weissella in the pickling system were the predominant microbial communities at the earlier phase. After 10d of fermentation, the dominant population had changed to be Lactobacillu and Alcaligenes. In the later stage of pickling process, the community system was stable, and Alcaligenes, Bacteroides and Clostridium were major species. Meanwhile, the pH value, nitrite concentration and the total population of bacteria of pickled amaranth stem increased at the first phase, then decreased and finally reached the values of 5.28, 4.0mg/kg and 1.0×107cfu/mL, respectively. The GC-MS analysis was used to identify the volatile flavor compositions in pickled amaranth stem. Results showed that the main volatile components in pickled amaranth stem products were alcohols, organic acids and alkanes. They account for 19.5%, 15.9% and 14.6%, respectively. Volatile compounds with relatively high contents were 2-butyl alcohol, ethanol, hexane and acetaldehyde, respectively.