Microbial biomass and community structure were investigated during stacking fermentation in the production of Sesame-flavor Liquor using the phospholipid fatty acid technique.The results indicated that the types and number of microorganisms PLFAs shows certain variation rules,and that can be a reflection of changes in microbial community structure.Straight chain saturated fatty acids and even-carbon unsaturated fatty acids were the predominant PLFAs.The impact of stack temperature and time on microbial biomass was obvious.Besides,the predominant microorganism is bacteria and G~-is the predominant bacteria during stacking fermentation.The difference between anaerobic and aerobic bacteria is quite visible in different samples.