Abstract: To investigate the microbial community structure and composition in concentrated tobacco liquid used for producing paper-making reconstituted tobacco and the effects of microbial fermentation on the properties of concentrated liquid, Illumina MiSeq sequencing platform was used to analyze 18S rDNA sequences in fungi and 16S rDNA sequences in bacteria from concentrated liquid of paper-making reconstituted tobacco supplied by Henan Cigarette Industrial Reconstituted Tobacco Sheet Limited Corporation. The community composition and abundance of fungi and bacteria in concentrated liquid were obtained, and the influences of fermentation duration (24, 48 and 72 h) on the reducing sugar and total sugar contents in concentrated liquid and the sensory quality of reconstituted tobacco were analyzed. The results showed that 548 and 5 295 OTUs (Operational Taxonomic Unit) were obtained in 18S rDNA of fungi and 16S rDNA of bacteria from the concentrated liquid of paper-making tobacco reconstituted sheets, respectively. The microbial community structure in the concentrated liquid was mainly fungi (80.98%) and a small amount of bacteria (19.02%). However, the amount of fungi was higher, while the abundance and diversity of fungi were lower than those of bacteria in the concentrated liquid. The dominant genera of fungi were Kazachstania, Candida and Ogataea. The dominant genera of bacteria were Lactobacillus, Streptococcus and Aeribacillus. The contents of reducing sugar and total sugar in concentrated liquid decreased greatly after fermentation for 48 to 72 h at 30℃. The comfortableness and aroma quantity of cigarette smoke can be promoted by fermenting the concentrated liquid for 72 h at 30℃.